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Ti
TitaniumAl
Aluminium

47.86726.981

IWTA2023
7th International Workshop on Titanium Aluminides
J u n e 1 1 - 1 6 , 2 0 2 3 , To u l o u s e, F r a n c e

Programme & Abstracts
1

PROGRAMME OVERVIEW
SundayJune 11

MondayJune 12

Tuesday
June 13

WednesdayJune 14

ThursdayJune 15

FridayJune 1608:30 - 10:10

08:30 - 09:50

08:30 - 09:50

08:30 - 09:50

08:30 - 10:00

Processing& Applications

Fundamental

Fundamental

Additive
Manufacturing

Coffee BreakCoffee BreakCoffee BreakCoffee Break

10:20 - 11:20

10:20 - 11:50

10:20 - 11:20

Coffee Break

10:40 - 12:10

Additive
Manufacturing

Processing& Applications

10:30 - 12:00

Additive
Manufacturing

11:20 - 12:30

Alloy
Properties

Posters

Lunch
12:30 - 14:00

Lunch
12:30 - 14:00

11:20 - 12:30

Alloy
Properties

Summary& Discussion

Posters
Buffet12:00 - 13:00

Lunch
12:30 - 14:00

Buffet &Departure
12:00 - 13:30

13:00
14:00 - 15:40

14:00 - 15:40

14:00 - 15:40

Processing& Applications

Processing& Applications

Processing& Applications

Coffee BreakCoffee BreakCoffee Break

16:10 - 17:50

16:10 - 18:00

16:10 - 18:00
Tour & Banket

Fundamental

Alloy
Properties

Fundamental

17:00
Registration
18:00
Welcome Party

2

PROGRAMME
Sunday, June 11

pages

Registration & Welcome party at the Mercure Hotel
From 17:00

Registration

From 18:00

Welcome Party

Monday, June 12
Session 1 - Processing & Applications
8:30-8:40

Welcome

8:40-9:20

KeynoteBernardBewlay9:20-9:50

InvitedPierreSallot9:50-10:10

Oral

Masao

Takeyama

Chairman: Volker Guether
The Science and Technology of TiAl Alloys For Commercial
Aircraft Engines
γ-TiAl alloys for aeronautical applications: a status of theirindustrial implementation, development opportunities andRevolutionary Approach to Develop Novel TiAl Alloys for
LPT Blades under SIP Program in Japan

21
22
23

Break: 10:10-10:40

Session 2 - Additive Manufacturing

Chairman: Marc Thomas
Microstructure Design of Titanium Aluminides by Additive
Manufacturing
Insight into Additive Manufacturing by combining in situ
diffraction and modelling

10:40-11:10

InvitedChristoph

Leyens24

11:10-11:30

Oral

FlorianPyczak11:30-11:50

Oral

MarcusRackel

TiAl powder based Composite Extrusion Modeling26

11:50-12:10

Oral

Yoshihiko

NagataInvestigation of alloy composition and identification ofprocess challenges for additively manufactured gamma-

27

25

Lunch: 12:30-14:00

Session 3 - Processing & Applications

Chairman: Wilfried Smarsly
Superior Productivity and Properties of Newly Designed
Wrought and Cast TiAl Alloys for Jet Engine Blade
FastCast - levitation melting & high-quality TiAl casting up
to 600 g

14:00-14:30

InvitedMasafumi

Kurashige

14:30-15:00

InvitedSerjejs

Spitans

15:00-15:20

Oral

Seong-Woong Kim

Development of TiAl alloys for gas turbine engines30

15:20-15:40

Oral

HidekiMicrostructure and Mechanical Properties of Reactively
Sintered TiAl based Alloys

31

Wakabayashi

28
29

Break: 15:40-16:10

Session 4 - Fundamental

Chairman: John Lewandowski

16:10-16:40

Invited

David

Holec

16:40-17:10

InvitedHirotoyo

Nakashima

17:10-17:30

Oral

YoshihiroGohda

17:30-17:50

Oral

Frank

Stein

Modelling of phase transformations in TiAl-based alloys
Computational Alloy Design of TiAl alloys applicable toPowder Processes
First-principles study of transition-metal β stabilizers in Ti-AlO
Stability, Composition Range, and Phase Equilibria of the
Nb-stabilized, TiAl-based phases ωo and O

3

32
33
34
35

Tuesday, June 13

pages

Session 5 - Fundamental

Chairwoman: Heike Gabrish

8:30-9:00

InvitedRuiYang

9:00-9:30

InvitedMaria

Nó

9:30-9:50

Oral

MichaelMusi

Formation and evolution of defects that interrupt lamellar
microstructure in cast TiAl alloys
High-Temperature Microstructure Evolution of an
Advanced Intermetallic Nano-Lamellar γ-TiAl Alloy
The effect of zirconium on phase stabilities andmicrostructure in the Ti-(42-46 at.%)Al alloy system

36
37
38

Break: 9:50-10:20

Session 6 - Additive Manufacturing

Chairman: Kui Liu

10:20-10:50

Invited

Marc

ThomasAdditive Manufacturing of Gamma Titanium Aluminides: A
Review of Methods, Properties and Challenges

10:50-11:20

InvitedKarin

Ratschbacher Production of intermetallic, spherical powders

40

Chairmen:
H.Nakashima & J.-P. Monchoux

Session 7 - Posters
Posters

11:20-12:30

39

75

Session 1

Lunch: 12:30-14:00

Session 8 - Processing & Applications
14:00-14:30

Invited

Alain

Couret14:30-15:00

InvitedAkira

Fukushima

15:00-15:20

Oral

ArnaudFregeac

15:20-15:40

Oral

Tadayuki

HanadaChairman: Pierre Sallot
Development of the TiAl IRIS alloy by Spark Plasma
Sintering
Development of TiAl turbine blade with metal injection
molding process
FAST/SPS: NEW industrial post-process for full densificationof 3D TiAl complex shape from additive manufacturing

41
42
43
44

Application of MIM process to TiAl Turbine Blade

Break: 15:40-16:10

Session 9 - Alloy properties

Chairman: Mauro Filippini
Microstructural Heterogeneity and Post Processing Effects

16:10-16:40

InvitedJohn

Lewandowski on Mechanical Properties of Ti-48Al-2Cr-2Nb Additively

16:40-17:00

Oral

MurielHantcherli

Influence of some promising alloying elements on themechanical properties and deformation mechanisms of TiAl

46

17:00-17:20

Oral

Alexander

Donchev

High Temperature Oxidation of g - TiAl Alloys: Effect of Zr

47

17:20-17:40

Oral

Toshimitsu Tetsui

Effects of Various Factors on the Impact Resistance of TiAl
Alloys48

17:40-18:00

Oral

Lin

Deformation twins in α2-Ti3Al phase

49

Song

4

45

Wednesday, June 14

pages

Session 10 - Fundamental

Chairman: Helmut Clemens

8:30-9:10

KeynoteMasao

Takeyama

9:10-9:30

Oral

MohamedKeita

9:30-9:50

Oral

Kazuhiro

MizutaAn Overview on “Materials Integration” for Revolutionary Design System of Structural Materials in SIP in Japan
Lamella orientation control of β-Solidifying TNM Alloys via
High-Temperature Compression
Effect of Microstructure on Creep Properties of TiAl4822
Built by Selective Laser Melting

50
51
52

Break: 9:50-10:20

Session 11 - Alloy properties

Chairman: José María San Juan

10:20-10:50

Invited

Mauro

Filippini

10:50-11:10

Oral

Guy

Molénat11:10-11:30

Oral

JonathanPaul

11:30-11:50

Oral

PascaleKanoutéFatigue cracking in additively manufactured gamma-TiAl
Plasticity and brittleness of the ordered Beta-o phase in a
TNM-TiAl alloy
Embrittlement after high temperature exposure: overview
of the literature in view of new findings
Study of fatigue mechanisms at the microstructure level in
TiAl alloys

53
54
55
56

Buffet: 12:00-13:30 and departure for the tour and banket

Thursday morning, June 15
Session 12 - Additive Manufacturing
8:30-9:00

InvitedHiroyuki

Yasuda9:00-9:30

InvitedIsak

Elfström

9:30-9:50

Oral

Ken

Cho

Chairman: Florian Pyczak
Microstructure Control of TiAl Alloys by Additive
Manufacturing
A simulation-based approach for EBM additive
manufacturing of γ-TiAl
Microstructure and Mechanical Properties of Additively
Manufactured β-containing TiAl Alloys

57
58
59

Break: 9:50-10:20
Session 13 - Processing & Applications
10:20-10:50

InvitedMelissaAllen

10:50-11:20

InvitedTomohiro

Nishimura

Solid solution Strengthening of TiAl alloys with Zirconium,
mechanical properties
Development of Rapid Determination Technique of Molten
TiAl Alloys using X-ray Fluorescence

60
61

Chairmen:
H. Nakashima & J.-P. Monchoux

Session 14 - Posters
11:20-12:30

Chairwoman: Sara Biamino

Posters

75

Session 2

Lunch: 12:30-14:00

5

Thursday afternoom, June 15
Session 15 - Processing & Applications
14:00-14:30

InvitedS. Biamino M. Galati

14:30-15:00

InvitedAndersEngström

15:00-15:20

Oral

Kui

Lui

15:20-15:40

Oral

Kenji

Doi

pages

Chairwoman: Melissa Allen
Progress on Titanium Aluminides within the NEWTEAM EU
project
Data to aid materials design and process optimization of
Titanium Aluminides
Cost-effective Vacuum induction melting of gamma TiAl
and NiTi alloy
Control of lamellar colony size in sintering process forinjection-molded TiAl alloys

62
63
64
65

Break: 15:40-16:10
Session 16 - Fundamental

Chairman: Rui Yang
How elaborate in situ experiments guide modern alloy

16:10-16:40

InvitedPetra

Spoerk-Erdely development

16:40-17:00

Oral

José María San Juan

17:00-17:20

Oral

Heike

Gabrisch

17:20-17:40

Oral

YuzhengZhang

17:40-18:00

Oral

Xiaobing

Li

66

Relaxation Mechanisms and Diffusion Processes in γ-TiAl
Intermetallics
Microstructure and elastic properties in Ti-42Al-8.5Nb after
long-term annealing at 550°C
The Role that Hot Deformation Plays in Determining theStatic and Dynamic Mechanical Behavior of a High Niobium
Thermal stability in microstructure of Mn containing βsolidifying γ-TiAl alloy

67
68
69
70

Friday, June 16
Session 17 - Alloy properties

Chairman: Bernard Bewlay

8:30-9:00

InvitedMathiasGaletz9:00-9:20

Oral

NadineLaska

9:20-9:40

Oral

Christoph

Breuner

9:40-10:00

Oral

Ryosuke

Yamagata

Oxidation Behavior of TiAl Alloys, its Influence on the
Mechanical Properties and Mitigation Strategies via
Deposition of Ti2AlC MAX-phase based coating on
Titaniumaluminides to improve the oxidation resistance
Influence of oxidation protective coatings on the hightemperature fatigue behaviour of Ti-48Al-2Cr-2Nb
Development of Microstructure Factor-based Mechanicalproperty Prediction Module for TiAl Alloys

Break: 10:00-10:30
Session 18 - Summary & discussion
10:30-11:40

Extended summary

11:40-12:00

Concluding remarks

Chairman: Masao Takeyama

Buffet: 12:00-13:30 & Departure

6

71
72
73
74

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Ti
TitaniumAl
Aluminium

47.86726.981

IWTA2023
7th International Workshop on Titanium Aluminides
J u n e 1 1 - 1 6 , 2 0 2 3 , To u l o u s e, F r a n c e7

8

Table of contents

Welcome message................................................................................................................................. 11
Organisation .......................................................................................................................................... 13
General information ............................................................................................................................. 15
Social program ...................................................................................................................................... 17
Abstracts Keynotes, Invited Talks & Oral Presentations ...................................................................... 19
Abstracts Posters .................................................................................................................................. 75
Index of authors and co-authors .......................................................................................................... 89
Index of participants ............................................................................................................................. 95
Notes .................................................................................................................................................... 99

9

10

Welcome message
Dear colleagues and friends,
On behalf of the International and Local Organizing Committees of the IWTA-2023, I am very pleased
to welcome you all to Toulouse.
Building on the resounding success of IWTA-2016 held in Tokyo, Japan, a new workshop planned andorganized by Bernard Bewlay and General Electric was scheduled to take place in the US in 2020.
Unfortunately, because of the Covid pandemic, this event, as well as a second proposal in 2021, werecancelled. In May 2022, the international committee requested the Toulouse group to host a workshop
in 2023. Guy Molénat, Jean-Philippe Monchoux, Muriel Hantcherli, and I agreed to take up thechallenge. We have put in a great deal of effort in the last year, and our reward today, is your presencein Toulouse, coming from France, Europe, Asia, and America; we are now close to one hundred instrength. This would not have been possible without the solid support of the international committee,
with whom we met once a month via a video conference that took place spanning early hours in theUS, late evening in Asia, and coinciding with the afternoon siesta time in Europe. To this effort, mythanks go to Guether Volker, Helmut Clemens, Masao Takeyama, Bernard Bewlay, Rui Yang, John
Lewandowsk and Hirotoyo Nakashima.
IWTA Workshops serve to provide a suitable platform for researchers and professionals working bothin academia and in industries worldwide, to discuss and exchange views on the recent progress andfuture perspectives on the properties, microstructure, technologies, processing and development of
Titanium Aluminides. IWTA Workshops are unique in that they bring engineers and researchers
together for a week of intense discussions on TiAl alloys in a relaxed setting. Another important aim of
IWTA is to welcome our new and young colleagues into the community.
IWTA-2023 is the seventh in the well-known series of meetings that have marked the history of TiAl
alloys. Let us remember that General Electric revealed the use of TiAl blades in its aviation engines in
Bamberg in 2006. Many advances have resulted from our exchanges at the various workshops. IWTA2023 will undoubtedly make its mark in the history of TiAl alloys, within the context of the ongoingenergy transition and the associated breakthroughs in terrestrial and aeronautical engines. These
breakthroughs are anticipated to create an increased demand for materials that are both lightweightand capable of high performance at high temperatures.
We would like to express our gratitude to our sponsors and partners who have helped to organize
IWTA-2023, which was made possible by the active participation of the members of the international
committee. Their logos are displayed on the back cover of this book. To them, we say Thank you very
much!!!
During this week, we offer you a balanced program that includes keynote lectures, invited talks, oralpresentations, and poster sessions. With a visit to Airbus and dinner at a vineyard, we look forward to
an exciting Wednesday afternoon and evening. Don't miss these!!!
Finally, we would like to thank all the speakers, presenters, and participants, whose participation isundoubtedly key to the success of IWTA-2023.
Enjoy the workshop and enjoy your stay in Toulouse,
Alain Couret

11

12

Organising Committee
Bernard Bewlay, GE Global Research, USA
Helmut Clemens, Montanuniversität Leoben, Austria
Alain Couret, CEMES-CNRS, France
Volker Güther, GfE Metalle und Materialien GmbH, Germany
John Lewandowski, Case Western Reserve University, USA
Hirotoyo Nakashima, Tokyo Institute of Technology, Japan
Masao Takeyama, Tokyo Institute of Technology, Japan
Rui Yang, Institute of Metal Research, China

Local Executive Committee
Alain Couret
Muriel Hantcherli
Guy Molénat
Jean-Philippe Monchoux
CEMES-CNRS, Toulouse, France

International Advisory Board
Mauro Filippini, Politecnico di Milano, Italy
Akira Fukushima, MHIAEL, JapanDavid Furrer, Pratt & Whitney, USA
Mathias Galetz, DECHEMA, Germany
Hitoshi Ishida, Kobe Steel Ltd., Japan
Nigel Martin, Rolls-Royce, UK
Yoshinao Mishima, Tokyo Institute of Technology, Japan
Jean-Philippe Monchoux, CEMES-CNRS, France
Florian Pyczak, Helmholtz-Zentrum Hereon, Germany
Silvia Sabbadini, GE Avio, Italy
Pierre Sallot, Safran, France
Jose San Juan, University del Pais Vasco, Spain
Petra Spoerk-Erdely, Montanuniversität Leoben, Austria
Kazunori Tahara, IHI Corporation, Japan
Marc Thomas, ONERA, France

13

14

General information
Venue
Hotel Mercure Toulouse Centre Compans
Boulevard Lascrosses
8 Esplanade Compans Caferelli
31000 Toulouse, France

GPS: 43.610705, 1.434822+33 561 11 09 09
H1585@accor.com

Metro: Compans-Cafarelli station, line B (station right in front of the hotel)
From the Toulouse-Blagnac airport:
Aerobus every 20 minutes, 15-minute drive, 9 €, stop right in front of the hotel | 8 km by car
From the Matabiau main railway station:
3 metro stations away, one change, 15 minutes | 2.2 km by car

15

16

Social program for Wednesday afternoon, June 14
1pm: Departure by bus from the Mercure hotel
1.30pm: arrival at Aeroscopia and identity check2.00pm-3.30pm: Group A (see letter indicated on the badge) visits the Airbus assembly line
2.30pm-4pm: Group B visits the Airbus assembly line
Waiting for and returning from the Airbus visit: each group visits the Aeroscopia museum(unaccompanied tour)
5pm: departure for Château Lastours
6pm-7pm: visit of the vineyards, the cellars and wine tasting in three groups (see number 1, 2 or 3
indicated on the badge)
7pm: dinerVisit of the Airbus assembly line

https://www.manatour.fr/en/airbus
Meeting address:
Aeroscopia museum, see below

Visit of the Aeroscopia museum

www.aeroscopia.fr
Allée André Turcat, 31700 Blagnac
Tram : Line 1 / Beauzelle Aeroscopia stop

Diner in the vineyard of Château Latours

www.chateau-lastours.com
81 310 Lisle-sur-Tarn (60 km from the hotel)

17

18

Abstracts
Keynotes,
Invited Talks & Oral Presentations(in chronological order – see programme)

19

20

Keynote
The Science and Technology of TiAl Alloys For Commercial
Aircraft Engines
B. P. Bewlay1 and M.J. Weimera

GE Research, One Research Circle, Niskayuna, NY, 12309, United States

Abstract
The present presentation will discuss development of the science and technology ofTitanium aluminide (TiAl)-based alloys that has culminated in their use in commercial aircraft
engines. Titanium aluminide (TiAl)-based alloys have been developed for high performance
applications in the aerospace industry. Within the last decade, TiAl alloys have been introduced
into service in a range of commercial aircraft engines as a new lightweight low pressure turbine(LPT) blade material class. The TiAl alloy 48-2-2 is extensively used in GEnxTM, LEAP-XTM,
and GE9XTM engines. In addition, a new -stabilized TiAl alloy (TNM) has been introduced asa LPT material for PW1100GTM engines. The mechanical properties of TiAl alloys are sensitive totheir microstructure, which is controlled by the alloy chemistry and processing schemes. This

review will focus on room and elevated temperature mechanical and environmental properties
exhibited by second and third generation TiAl alloys. In terms of component manufacturing,
conventional

casting,near-net-shapecasting,high-temperatureforging,andadditive

manufacturing approaches will be discussed.

1

Corresponding Author. Tel. +1 (518) 387-6121;. E-mail address: bewlay@ge.com.

21

Invited Talk

γ-TiAl alloys for aeronautical applications: a status of theirindustrial implementation, development opportunities andchallenges
Pierre SALLOT1*
Safran Tech, Materials and Processes, Rue des Jeunes Bois, Châteaufort,
78114 Magny-Les-Hameaux, France*corresponding author

Titanium aluminide has been for years identified as a solution for weight reduction in the LPT(Low Pressure Turbine) of a turbo-engine. The improved specific mechanical properties of theseintermetallic alloys, when compared to Ni-based superalloys, have pushed Safran and other major
aero-turbine producers to introduce them in their newest generations of turbines. Today, TiAl
LPT blades are a reality for mass production.
In the present study, several processing routes to produce complex TiAl parts are investigated,from isothermal forging to powder metallurgy, and their impact on alloy properties compared. It
will be used as a basis for discussion on material developments, but it will emphasize as welllimitations to overcome for next generation applications. To support it, metallurgicalcharacterizations as well as specific mechanical trials will be used to exemplify these points, witha focus on oxidation resistance.
A specific part of the presentation will be dedicated to the introduction of a new Powder
Metallurgy route using Spark Plasma Sintering and its application to industrial parts. Material
microstructures and properties will be compared to other processes, but also its energy
consumption will be discussed.
In term of perspectives, remaining challenges in the development of these alloys will beemphasized and discussed.

22Oral Presentation
Revolutionary Approach to Develop Novel TiAl Alloys for LPT
Blades under SIP Program in Japan
Masao Takeyama*
Department of Materials Science & Engineering, School of Materials and Chemical Technology,
Tokyo Institute of Technology, Tokyo, Japan*corresponding author

In the past decade, two consecutive five-year national projects of “Structural Materials forInnovation (SM4I)” (2014-2018) and “Materials Integration for Revolutionary Design System ofStructural Materials” (2018-2022), mainly focusing on jet engine parts, were conducted in Japan
under the Cross-ministerial Strategic Innovation Promotion Program (SIP). The R & D of TiAl
blades were one of the main subjects in the projects, and I was committed to them as a technicalleader and took responsibility for the novel alloy design of titanium aluminides for LPT blades injet engines, in collaboration with industries and other universities, based on our newly integrated
design principles. In the first project, the focus was placed on the innovative wrought/cast TiAl
alloys, whereas the powder processed alloy development, such as MIM (Metal Injection
Molding) and AM (Additive Manufacturing), was focused in the second program, in terms of theintegrated inverse design approach. In both programs, we have successfully developed novel
alloys superior to the currently existing alloys.
In this talk, although detailed approaches and process developments will be emphasized by theindividual presentations from academia and industries in this workshop, I will introduce thewhole images of industry-academia collaboration team roles and several important points for the
revolutionary alloy developments. Regardless of the different fabrication processes of cast,wrought, MIM and AM, an underlying principle is in the reliable multi-component phase
diagrams, especially oxygen. You must realize how oxygen level is so sensitive to change thephase relationship among the phases concerned in the developed alloys, resulting in significant
change in microstructure even the major alloy elements as well as the heat treatment routes are
the same. Our integrated computational inverse alloy design system consisting of two modules of
MPM (mechanical-property prediction module) and MDM (Microstructure Design module) will
also be touched, in addition to the importance of introducing bcc b-Ti phase in the microstructure
for mechanical property improvements.
A part of this study has been carried out under the research of SIP in JST (Japan Science andTechnology Agency).

23

Invited Talk
Microstructure Design of Titanium Aluminides by Additive
Manufacturing
Christoph Leyens1,2*, Juliane Moritz1,2, Axel Marquardt1,2, Mirko Teschke3, and Frank Walther3
1

Technische Universität Dresden, Institute of Materials Science (IfWW), Helmholtzstr. 7, 01069 Dresden, Germany
2
Fraunhofer Institute for Material and Beam Technology IWS, Winterbergstr. 28, 01277 Dresden, Germany
3
TU Dortmund University, Department of Materials Test Engineering (WPT), Baroper Str. 303, 44227 Dortmund,
Germany*corresponding author

Titanium aluminides, including the TNM-B1 alloy (Ti-43.5Al-4Nb-1Mo-0.1B), have been
attracting continuous research interest due to their potential for lightweight high-temperatureapplications. Nevertheless, conventional processing of titanium aluminide alloys remains
challenging as a consequence of their pronounced brittleness. Additive manufacturing can be a
viable alternative for the near-net-shape production of titanium aluminide components. Electron
beam powder bed fusion (PBF-EB) is particularly suitable for this purpose, as the high processtemperatures above the brittle-to-ductile transition temperature allow crack-free processing.
However, due to the processing under vacuum and the different vapor pressures of the alloying
elements, aluminum tends to evaporate from the melt. The extent of the occurring aluminum loss
is closely related to the selected process parameters. Pronounced aluminum evaporation does not
only have an impact on the overall chemical composition of the component, but can also affectphase transformation temperatures and microstructure evolution during heat treatment.
While these evaporation effects are undesirable in many cases, the aluminum content can also be
specifically adjusted by an adequate selection of the melting parameters in PBF-EB. By
controlling the aluminum content in different areas of a component, tailored microstructures canbe achieved via subsequent two-step heat treatments (see Figure 1) [1]. For example, this mightenable the adjustment of a fully lamellar microstructure with high creep resistance in the blade
and a more ductile nearly lamellar γ-microstructure in the blade root within the same turbine
blade component [2]. This contribution will provide a detailed insight into the correlation
between the PBF-EB process conditions and the resulting microstructures with respect to atargeted microstructure design. Furthermore, challenges regarding microstructural homogeneity
originating from the layer-wise manufacturing as well as ways to overcome these issues will be
addressed.

Figure 1: Local adjustment of microstructures and properties within the same component via PBF-EB processparameter variation and subsequent heat treatment [1]References[1]
J. Moritz, M. Teschke, A. Marquardt, L. Stepien, E. López, F. Brueckner, F. Walther, C.
Leyens, Locally Adapted Microstructures in an Additively Manufactured Titanium
Aluminide Alloy Through Process Parameter Variation and Heat Treatment, Adv Eng
Mater. (2022) 2200917. https://doi.org/10.1002/adem.202200917.
[2]
J. Knörlein, M.M. Franke, M. Schloffer, C. Körner, In-situ aluminum control for titanium
aluminide via electron beam powder bed fusion to realize a dual microstructure, Additive
Manufacturing. 59 (2022) 103132. https://doi.org/10.1016/j.addma.2022.103132.
24

Oral Presentation
Insight into Additive Manufacturing by combining in situ diffraction
and modelling
Adriana de Andrade1, Florian Pyczak1*, Marcus Rackel1, Jan Rosigkeit1, Andreas Stark1, Peter
Staron11Institute of Materials Physics, Helmholtz-Zentrum Hereon, Max-Planck-Strasse 1, 21502 Geesthacht, Germany*corresponding author

Additive manufacturing (AM) is an important up-coming processing route for TiAl alloys. It
provides inherent advantages like its near net shape processing capability and the good chemical
homogeneity of the parts produced by powder based AM methods. Due to the low ductility of
TiAl alloys, compared to conventional alloys, the high heating and cooling rates experienced
during AM can cause cracking and damage. The complex phase diagram of TiAl alloys
exacerbates this problem. It shows a number of phase transformations between melting point androom temperature, which may be associated with volume change or volume misfits between
phases. At lower temperatures, TiAl parts are too brittle to withstand the stresses caused by thosevolume changes and misfits and will fail during AM, making pre-heating essential.
In this contribution, the results of the characterization by high-energy X-ray diffraction of TiAl
alloys under AM conditions are presented. Directly after solidification, the phase constitution of
TiAl resembles very closely the phase constitution directly at the liquid-solid transition. The final
microstructure and phase constitution forms in the layers below the surface. These experience a
cyclic heat treatment due to the melting and solidification of the on top powder layer. The
maximum temperature of this thermal cycle decreases with increasing distance from the top layer.
From the development of lattice constants and phase fractions, it is possible to reconstruct theinternal processes in the material during this complex heat treatment scheme. However, the phase
constitution and microstructures are far away from equilibrium. Only by a combination of direct
measurements and modeling one can unveil the situation in the material and acquire theknowledge necessary to optimize the process or adapt the material to the process.

Figure 1: Temperature profile of a cyclic heat treatment to simulate AM (grey solid line) and measured lattice
constants of  phase (solid blue lines) in comparison with model predictions (dashed red lines)

25

Oral Presentation
TiAl powder based Composite Extrusion Modeling
Marcus Willi Rackel1*, Jonathan David Heaton Paul1, Wolfgang Limberg2, Stephan Schulze1,
Henrik Lüneburg2, Kai Hendrik Steinberg2, Florian Pyczak1
1Helmholtz-Zentrum hereon GmbH, Institute of Materials Physics, Max-Planck-Straße 1, 21502 Geesthacht,
Germany.
2Helmholtz-Zentrum hereon GmbH, Institute of Metallic Biomaterials, Max-Planck-Straße 1, 21502 Geesthacht,
Germany.
*marcus.rackel@hereon.de

In this paper, a first attempt was made to process TiAl alloys using the Composite Extrusion
Modeling (CEM) process. The achieved properties are compared to those of material made using
a standard Metal Injection Moulding (MIM) process route.
One advantage of the CEM process is that the existing technical infrastructure of the wellestablished MIM processing route can be used. The CEM process combines this with theadvantages of additive manufacturing processes such as high geometrical degree of freedom andoptimised material use. Thus material and machine costs can be reduced. Furthermore, process
induced residual stresses and their negative influence on components properties are negligible
compared to powder bed-based additive manufacturing processes such as laser or electron beamfusion.
The first step in the process was the production of spherical TNM alloy powder (Ti-43.5Al-4Nb1Mo-0.1B, in at.%) at Helmholtz-Zentrum Hereon using the Electrode Induction Melting Inert
Gas Atomization process. After sieving, the powder fraction < 25 µm was used for the
preparation of a paraffin based binder feedstock. Thereafter, the feedstock was granulated to 1–
3 mm diameter particles and dog bone shaped samples were produced, using an
AIM3D ExAM 255 printer for CEM processing and an Arburg 370A injection moulding machinefor MIM processing. Subsequently, all the samples produced were thermochemically debinded
and then sintered in an inert argon gas atmosphere. The resulting microstructures and phases wereanalysed using SEM and EBSD, as well as high energy X-ray diffraction.
For both the CEM and MIM production techniques, tensile tests were performed at room
temperature. In addition, compression creep tests were carried out at two different temperatures,
700 °C and 800 °C, under 150 MPa load.

Figure 1:a) CEM printing of a TNM demonstrator part. b) Finished demonstrator partmade out of TNM alloy after printing, thermochemical debinding and sintering.

26

Oral Presentation

Investigation of alloy composition and identification ofprocess challenges for additively manufactured
gamma-titanium aluminides
Yoshihiko Nagata1*, Yutaro Ota1, Rachel Jennings2, Noriko Read2, Koji Nezaki1, Sadao
Nishikiori1*
1

Technology & Intelligence Integration, IHI Corporation, 1, Shinnakahara-cho, Isogo-ku, Yokohama
235-8501, Japan2

IHI Europe Ltd. 2nd Floor, America House,2 America Square, London EC3N 2LU, U.K.
*nagata7192@ihi-g.com Yoshihiko Nagata

Gamma titanium aluminides (γ-TiAl) has been expected to replace existing Ni-based
superalloys (Alloy 718) due to its low density and superior specific strength at hightemperature. In an effort to make γ-TiAl alloys more widely applicable as structural
materials, development projects have been vigorously pursued over the past 30 years in
Europe, the United States, and Japan, mainly by the aeroengine industry, the materials
industry, and research institutes. In particular, the project conducted by GE in 1995
succeeded in the ground test of the engine using TiAl alloy for LPT blades, which gavea great impetus to the practical use of TiAl. IHI has accumulated knowledge ofprecision casting technology to ensure a practical level of quality.
Since 2000, there has been a growing demand from the automotive industry forturbocharger blades made of TiAl alloy instead of Alloy 713C, and IHI has developed afully lamella-TiAl alloy with improved creep strength in the temperature range of1175K to 1275K. Utilizing these advanced technologies and building a supply system,
IHI began mass production in 2004 and has produced well over 160,000 units.
In order to expand the application of TiAl beyond aircraft engine blades andturbocharger airfoils, we believe that a new manufacturing method, especially additive
manufacturing (AM), will be effective. In this presentation, we will discuss the alloy
design guideline based on the reintroduction of elements whose addition was restrictedby conventional production methods due to segregation problems. The degradation
phenomenon of TiAl airfoils used for more than 10 years as turbochargers for vehicles
will also be discussed. Furthermore, in the AM process development, we will focus on
the electron beam melting (EBM) method and extract engineering issues that affect theprocess and quality stability. For example, we will investigate the smoke phenomenon
characterizing the dependence of each powder particles variable, and deepen thediscussion and sharing of results with the participants to work towards a solution.

27

Invited Talk
Superior Productivity and Properties of Newly Designed Wrought andCast TiAl Alloys for Jet Engine Blade Components
Masafumi Kurashige1*, Keiji Kubushiro2, Yohei Sakakibara3, Yutaro Ota4, Satoshi Takahashi5,
Masao Takeyama6
1

Aero Engine, Space & Defence Business Area, Research & Engineering Division, IHI Corporation
2
Asia Solution Center, IHI Asia Pacific Thailand Co.,Ltd.
3
Technology & Intelligence Integration, Technology Platform Center, IHI Corporation
4
Aero Engine, Space & Defence Business Area, Space Development Department, IHI Corporation
5
Engineering Division, IHI Castings Co., Ltd.
6
Tokyo Institute of Technology, School of Materials and Chemical Technology*kurashige6552@ihi-g.com Masafumi Kurashige

TiAl alloys are light-weight heat resistance material and have been applied to low pressure
turbine blades of civil aircraft engines represented by GEnx, LEAP and GE9X. The possibility of
TiAl alloys spread more in comparison with these conventional alloys. In this study, TiAl alloys
for forging and casting were developed according to established alloy design method. These
alloys, developed for next-generation jet-engine, have a good balance of strength, ductility atroom temperature and productivity. Tensile, creep and high cycle fatigue tests at elevatedtemperature were conducted for developed alloys and their results were superior to conventional
TiAl alloys, partly due to the effect of adjusting heat treatment conditions. Also, it wasdemonstrated that the developed alloys can be processed into low pressure turbine blade shapes
without harmful defects by casting or hot die forging using conventional techniques andequipment (not isothermal forging). These results will be able to achieve lower cost and expand
the jet-engine application range of TiAl alloys. The details of the processing route andperformances on the developed wrought and cast alloys will be presented.
This work was supported by Council for Science, Technology and Innovation(CSTI), Crossministerial Strategic Innovation Promotion Program (SIP), “Structural Materials forInnovation”(Funding agency : JST).

28

Invited Talk
FastCast - levitation melting & high-quality TiAl casting up to 600 g
Sergejs Spitans1, Henrik Franz1* , Christian Bauer1 , Björn Sehring1, Egbert Baake2
1

2

ALD Vacuum Technologies GmbH, Otto-von-Guericke-Platz 1, Hanau, Germany
Institute of Electrotechnology at Leibniz University Hannover, Wilhelm-Busch-Straße 4, Hannover, Germany*henrik.franz@ald-vt.de

Ti-alloys are highly reactive in liquid phase and must be melted in water-cooled copper
crucibles. A thin skull layer that forms at the cold wall prevents contamination, however, results inhuge thermal losses, low melt superheat and “cold-runner” defects in castings. Because of that,complex geometry turbocharger wheels and blades from hard-to-cast γ-TiAl are mostly machined.
Levitation melting, known since 1920’s, utilizes EM-field to confine metallic samples in acontact-free condition and has evident advantages in superior purity, no material loss in the skull
and significantly higher superheat. However, in conventional axisymmetric implementation only
small samples up to 50 g can be levitated and investment casting scale-up needs remain unsatisfied.
A novel levitation melting method that utilizes two horizontal and orthogonal EM-fields ofdifferent frequencies has been developed to solve the scale-up issue. Numerical modelling has beenused to design a new melting unit and to integrate it in a pilot investment casting furnace called
FastCast, capable of contact-free melting and single-shot casting of Ti- and Ni-alloys up to 600 g.
The demonstrator furnace is capable of 10 automated consecutive castings in vacuum or Argon
atmosphere. Melting starts as the lower end of the vertically oriented electrode is immersed in thelevitation melting unit. EM fields (installed power 180 kW) rapidly
melt up to 600 g of material from the tip of the electrode andsimultaneously confine the liquid metal in a contact-free condition. The
electrode is moved up and detached levitated melt is rapidly
superheated up to adjustable 250 C. Then EM field below the melt is
reduced and the melt falls down in the awaiting preheated mold.
Synchronized with the free-falling melt position, the mold isaccelerated vertically down following the pre-programmed recipe tocatch the melt and full-stop at the bottom of the casting chamber. Suchmold movement reduces relative velocity between the falling melt andthe mold at the moment of the contact, avoids splashing (>98% ofmaterial lands in the mould) and ensures smooth filling. On top of that,the mold table allows for the centrifugal casting up to 800 rpm. As thecasting is accomplished, the manipulator arm stores the filled mold andtakes the next preheated empty mold for the next cycle. Short melting
time (<100 s) per casting is a prerequisite for high productivity.
Ti-48-2-2 turbocharger wheel castings with 0.3 mm blade thickness revealed good surface
quality, high level of reproducibility and absence of cold runners even at low mould temperatures.
Defect-free filling of thin and complex sections has been approved by CT-scans.
The FastCast pilot system is available at ALD for customer visits and trials.

29Oral Presentation
Development of TiAl alloys for gas turbine engines
Seong-Woong Kim*
Titanium Department, Korea Institute of Materials Science, Changwon 642-831, South Korea* Corresponding author

Keywords: TiAl, gas turbine blade, high-temperature strength

Research on developing new TiAl alloys for high temperature applications is introduced. At KIMS, wehave developed new TiAl alloys which have excellent room temperature and high temperature properties.
Especially, the new alloy showed excellent oxidation resistance in the temperature range from 900 to
1000oC by forming stable Al 2O3 oxidation layer. Process developement of casting, forging as well as 3d
printing on the newly developed KIMS alloys was introduced. Especially, small size turbine wheel andblade were manufactured be centrifugal casting process. The results from the testing and validation of
TiAl blade were shown that KIMS alloy can be used as a turbine blade above 900 oC. In addition, we
proposed some underlying mechanism of high temperature strength of KIMS alloy from TEM and SEM
observations. Finally, the operation test of micro gas turbine is now under examination to confirm thepossibility of the application of the new alloy in the gas turbune engine.

30Oral Presentation
Microstructure and Mechanical Properties of Reactively Sintered
TiAl based Alloys
Hideki Wakabayashi1*, Fumio Tooyama2
1

Next Generation Tatara Co-Creation Centre, Shimane University, Shimane, Japan
2
Kiguchi Technics Inc., Shimane, Japan* corresponding author

Microstructure and mechanical properties of -TiAl based alloys prepared by reactive
sintering of pure metal powders have been investigated. Metal powders of Ti, Al and M (M:transition metal elements) were mixed to obtain a composition of Ti-45Al and Ti-45Al-4M(at. %) . Mixed powder was then heated to a temperature range from 1073 K to 1573 K by spark
plasma sintering to produce sintered compacts with a diameter of 30 mm and a height of 7 mm.
The mechanical properties of the alloys were evaluated by three-point bending tests. The densityof sintered Ti-45Al compacts increased from 3.3 to 3.9 g/cm3 as the sintering temperature
increased from 1073 K to 1573 K. That of Ti-45Al-4M alloys sintered at 1573 K shows
approximately 4.0 g/cm3, which is considered to be close to the theoretical density. The
microstructure of Ti-45Al alloy consists of -Ti3Al/ lamellar and grains. That of Ti-45Al-4M
alloys is composed of -Ti3Al/ lamellar grains, grains and  grains. The bending strength of
Ti-45Al alloy is about 700 MPa at room temperature and 800 MPa at 1273 K. Details of reaction
sintering process of pure metal powders and microstructural formation will be discussed inpresentation. This work was supported by the project, “Subsidy for Regional University /Regional Industry Creation” of the Cabinet Office, Government of Japan: "Creation of a Global
Base for Advanced Metals - Next Generation TATARA Project-".

31

Invited Talk
Modelling of phase transformations in TiAl-based alloys
David Holec1*
1

Department of Materials Science, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austria*david.holec@unileoben.ac.at

In this contribution, I will review our recent activities in applying Density Functional Theory(DFT) to phase stability problems and related phase transformations between various phases in amodel TiAl+Mo system. It is experimentally interesting to include the bcc phase at hightemperatures, which is, however, mechanically unstable in the binary stoichiometric TiAl
scenario [1]. Alloying Mo, this phase can be stabilized concerning both phases, the hexagonal
based on the α2-Ti3Al structure [2] and the distorted tetragonal γ-TiAl phase [3]. The DFT
calculated potential energy surfaces suggest that these martensitic transformations are mostly
barrier-less.
The chemical disorder was suggested as an effective stabilizing mechanism for the β-TiAl+Mo
system [1]. In comparison to the ordered phases mentioned above, the chemical disordersignificantly reduces the transformation driving force for both scenarios, β→α [2] as well as
β→γdis phases [3]. Moreover, small energy barriers appear for low Mo concentrations, thus
opening a possibility for metastable phases.
In the final part of my talk, I will present strategies for predicting ordering transformations [4].
The calculated ordering temperature Tord will be presented again for the TiAl+Mo model systemfor bcc β→βo and hcp α→α2 (B19) transformations.

(a)

(b)

(a) Example of α2(B19)↔βo↔γ transformation landscape for TiAl+Mo [2, 3, 5]. (b) Ordering α 2(B19)↔α for binary
TiAl [4].

32Invited Talk
Computational Alloy Design of TiAl alloys applicable to Powder Processes
Hirotoyo Nakashima*, Ryosuke Yamagata, Yoshihiro Gohda, Masao Takeyama
Department of Materials Science and Engineering, School of Materials and Chemical Technology,
Tokyo Institute of Technology, Tokyo, Japan*corresponding author

A microstructure design module for multi-component TiAl alloys has been developed as part of an
integrated computational inverse problem approach. This module outputs the alloy compositionand heat treatment conditions that will achieve the input of the volume fraction of the
microstructural constituents to meet satisfy the required properties, and thus provides for faster andlower-cost alloy design. This is achieved by combining the thermodynamic calculation and kinetic
modeling using the CALPHAD framework with ab-initio calculations.
With particular application to powder processes where oxygen contamination is a serious problem,the effect of oxygen in solution on the phase equilibria and phase transformation kinetics wasevaluated using an experimental forward problem approach. For the phase equilibria, soft X-ray
emission spectroscopy (SXES) combined with EPMA has revealed a strong α-Ti (or α2-Ti3Al)
stabilizing effect of oxygen and the resulting shift of the β-Ti + α + γ-TiAl three-phase tie-triangles
towards the higher M concentration side of the Ti-Al-M-O (M: transient metal elements) systems
with the oxygen addition. For the kinetics, oxygen is found to retard both nucleation and growth ofcells in the α + γ → β + γ cellular reaction. A set of databases has been constructed to reproduce
these experimentally determined oxygen effects on the basis of thermodynamic descriptions andclassical nucleation and growth theory. The combined computational design approach isdemonstrated by designing unique high performance alloys applicable for metal injection molding(MIM) and powder bed electron beam melting processes.
This study was supported by the Cross-Ministerial Strategic Innovation Promotion Program (SIP)“Structural Materials for Innovation” from the Japan Science and Technology Agency (JST).

33

Oral Presentation
First-principles study of transition-metal β stabilizers in Ti-Al-O
Ukyo Shibata1, Hirotoyo Nakashima2, Masao Takeyama2, Yoshihiro Gohda1*,
1

Dept. Mater. Sci. Eng., Tokyo Tech, 226-8502 Yokohama, Japan
2
Dept. Mater. Sci. Eng., Tokyo Tech, 152-8552 Tokyo, Japan*corresponding author

Eβ−Eα [eV]

In microstructures of Ti-Al alloys, the bcc β phase plays important roles as subphases in
exhibiting mechanical properties to prevent plastic deformations at high temperatures. In designingmicrostructures, additive metallic elements at substitutional atomic sites can be effective, e.g., Cr
and Nb as β stabilizers. On the other hand, oxygen atoms are included at interstitial sites in powderprocessed Ti-Al alloys. These interstitial oxygen atoms also affect phase equilibria modulating
microstructures that have been reported for Ti-Al-V and Ti-Al-Cr [1]. Thus, interplays between
interstitial oxygen and substitutional metallic elements should be considered in understanding
phase equilibria precisely. Even though knowledge of the systematic change in a transition-metalelement M will be helpful for deeper understanding, neither experimental nor theoretical studies
have been reported from this aspect. Particularly, the change in the effectiveness as a β stabilizer
is one of primary interests.
In this study, the structural stability of the β phase relative to the hcp α phase is examined fromthe viewpoint of electron theory. First-principles calculations are performed for random alloys by
the supercell approach containing 64 metallic atoms on the basis of density functional theory within
the generalized gradient approximation. One transition-metal M atom are substituted to a Ti siteand one oxygen atoms are included into an octahedral substitutional site. Since the β phase isunstable without help of anharmonic lattice vibrations at finite temperatures, the structural
optimization for the β phase is partial: i.e., impurity
atoms and their surrounding host atoms as well as
the lattice constant are optimized. Differences
between the full and partial structural relaxations
are confirmed to be sufficiently small for the α6phase.
First, we identify that oxygen is most stable atoctahedral interstitial sites consisting of 6 Ti atoms
in ternary Ti-Al-O alloys. The formation energy forthe oxygen interstitial is examined using totalenergies of ternary Ti-Al-M and quaternary Ti-AlM-O alloys, where M is examined for 3d and 4d
5transition-metal elements. The formation energy islower for early transition metals compared with latetransition metals, which can be partly explained byhigh ionicity of early transition metals. Even though
this tendency is common for both α and β phases,
Sc Ti V Cr Mn Fe Co Ni Cu Y Zr Nb Mo Tc Ru Rh Pd Ag
differences between the phases are also seen. Thus,
Transition metal elements, M
we compare total energies of the α and β phases. As Fig. Energy differences per M atom between theshown in Fig., oxygen hinders Nb from being a β α and β phases for Ti0.609Al0.375M0.016 (dark bars)
stabilizer significantly. Its detailed mechanism will and Ti0.600Al0.369M0.015O0.015 (light bars behinddark ones). Horizontal lines represent values for
be clarified in the presentation.
Ti Al
and Ti Al O .
0.625

0.375

0.615

0.369

0.015

[1] H. Nakashima and M. Takeyama, MRS Adv. 6, 195 (2021).

34

Oral Presentation
Stability, Composition Range, and Phase Equilibria of the Nbstabilized, TiAl-based phases ωo and O
Frank Stein1*, Benedikt Distl1, Katja Hauschildt2, Florian Pyczak2
1

Max-Planck-Institut für Eisenforschung, Düsseldorf, Germany
2
Helmholtz-Zentrum Hereon, Geesthacht, Germany*corresponding author

Nb is the most important alloying element in TiAl-based alloys. Depending on alloy composition
and thermal history, Nb-containing TiAl-based alloys may contain the ωo and O ternary phases.
These ternary compounds significantly affect the microstructure and mechanical properties and,
therefore, a detailed knowledge of their composition and stability ranges, as well as of the phaseequilibria and microstructures they form with the Ti-Al phases α-Ti, α2 (Ti3Al), β/βo-Ti, and γ(TiAl) is required.
A series of ternary Ti-Al-Nb alloys containing 17.5 to 45 at.% Al and up to 25 at.% Nb as well assome solid-solid and solid-liquid diffusion couples were prepared and annealed between 700 and
1000°C for up to 1500 h. The resulting microstructures and the types and compositions of phases
were analyzed by scanning electron microscopy (SEM), electron probe microanalyses (EPMA),
and high-energy X-ray diffraction (HEXRD) yielding isothermal sections at 700, 800, 900, and1000°C [1,2]. In addition, the phase transformations involving the decomposition/formation ofthe ωo and O phase were studied by differential thermal analysis (DTA) and in situ HEXRD [3].
The slow kinetics of these solid state phase transformations was analyzed by DTA experimentswith varying heating rates allowing the determination of the true equilibrium transformation
temperatures. The dependence of the measured transformation temperatures on the heating ratevaries systematically with the complexity of the transformations. Both, ωo and O phase are stable
to above 900°C. For the ωo phase, a new formula (Ti,Nb)2Al is suggested based on the measured
composition range and its crystal structure type. The results also indicate that the phase field of
the ωo phase is split into two parts at 900°C because of the growing phase field of the ordered βophase.
The research was carried out within the scope of the European Union Clean Sky 2 project
ADVANCE, which has received funding from the Horizon 2020 research and innovation
programme under grant agreement No 820647.

[1] B. Distl, K. Hauschildt, B. Rashkova, F. Pyczak, F. Stein, Phase equilibria in the Ti-rich part of the Ti-Al-Nb
system—Part I: Low-temperature phase equilibria between 700 and 900 °C, J. Phase Equilib. Diffus. 43 (2022) 355381. https://doi.org/10.1007/s11669-022-00963-8[2] B. Distl, K. Hauschildt, F. Pyczak, F. Stein, Phase equilibria in the Ti-rich part of the Ti–Al–Nb system—Part II:
High-temperature phase equilibria between 1000 and 1300 °C, J. Phase Equilib. Diffus. 43 (2022) 554–575.
https://doi.org/10.1007/s11669-022-00999-w[3] B. Distl, K. Hauschildt, F. Pyczak, F. Stein, Solid-solid phase transformations and their kinetics in Ti–Al–Nb
alloys, Metals 11 (2021) 1991. https://doi.org/10.3390/met11121991

35

Invited Talk
Formation and evolution of defects that interrupt lamellar microstructure in cast
TiAl alloys
Renci Liu, Ruxin Cao, Zhichun Zhou, Yuyou Cui, Rui Yang
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
Cast gamma TiAl alloys normally contain lamellar microstructure that ensures
excellent resistance to fatigue crack growth and to high temperature creep ofaeroengine components such as low pressure turbine blades. Extra alloying additions
are sometimes necessary to improve mechanical and service performance but, if notcontrolled properly, they may cause undesirable phases that may interrupt or evendestroy the lamellar microstructure. Typical examples include ribbon-shaped boride inboron containing gamma alloys that may cut through a lamellar grains and thus
provide a short cut for crack propagation, and formation of orthorhombic phase fromthe ordered hexagonal phase that may disintegrate the lamellar microstructure inalloys that contains a significant amount of heavy transition metals. In this talk, suchphenomena in cast 4522XD and TNM based alloys will be presented, and theconditions under which they appear will be analyzed.

36

Invited Talk
High-Temperature Microstructure Evolution of an Advanced
Intermetallic Nano-Lamellar γ-TiAl Alloy
Maria L. Nó1*, Thomas Klein2,3, Helmut Clemens3, Jose M. San Juan1
1

Dpt. Fisica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, Apdo 644, 48080-Bilbao,
Spain.
2
Austrian Institute of Technology, Lamprechtshausenerstraße 61, Postfach 26, 5282 Braunau am Inn, Ranshofen,
Austria.
3
Dpt. of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, 8700 Leoben,
Austria.
*corresponding author: maria.no@ehu.es

In recent years, engineering intermetallic γ-TiAl based alloys were introduced in the low-pressure
turbines of several aeronautic engines and nowadays thousands of blades are flying incommercial aircrafts.
To improve the present performances of these alloys, the creep resistance should be improved toallow an increase of the working service temperature, as well as a longer service life. Recently, a
new generation of γ-TiAl, Ti-43.3Al-4.0Nb-1.0Mo-0.3C-0.3Si (at%), called TNM+, wasdeveloped to improve the creep resistance by microalloying with C and Si [1] and developing afully nano-lamellar microstructure. The relaxation processes associated with the diffusion ofseveral atomic species were also studied [2]. The combination of very fine precipitates with thenano-lamellar structure makes this alloy exhibiting a high creep resistance [1]. However, toextend the creep resistance on temperature and on time, the stability of the microstructure should
be guaranteed or, as in the case of superalloys, well mastered in what concerns to its evolution.
In the present work, a complete study of the microstructure evolution in this nano-lamellar γ-TiAlalloy was carried out by transmission electron microscopy in a FEI Titan-Cubed G3 300 kV
aberration corrected on objective lens and Super-Twin EDX detector. The nucleation and growthof βo and ζ silicide precipitates were studied by TEM, HRTEM and HRSTEM-HAADF and theircomposition was quantitatively analysed by high-quality EDX maps. In addition, the orientation
relationships between them and also with the hosting phases, α2 and γ, were determined.
Simultaneously, the slow disintegration of the α2 phase when transforming into γ phase was alsostudied. Moreover, it was observed that the precipitates nucleate preferentially in the α2 phaseslowing down the process of disintegration of α2 phase and its transformation into γ phase. The
observed evolution of the microstructure is interpreted through the diffusion processes taking
place during the precipitation and α2 disintegration, which were determined through internal
friction measurements. Finally, the potential influence of the microstructure evolution on creep
resistance is discussed.
[1] T. Klein, L. Usategui, B. Rashkova, M.L. Nó, J.M. San Juan, H. Clemens, S. Mayer, Acta Mater. 128(2017) 440-450.
[2] L. Usategui, T. Klein, M.L. Nó, S. Mayer, H. Clemens, J.M. San Juan, Acta Mater. 200 (2020) 442454.

37

Oral Presentation
The effect of zirconium on phase stabilities and microstructure in
the Ti-(42-46 at.%)Al alloy system
Michael Musi1*, Stefan Kardos1, Melissa Allen2, Lukas Hatzenbichler1, David Holec1,
Andreas Stark3, Volker Güther2, Helmut Clemens1, Petra Spoerk-Erdely1
1

Department of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria
2
GfE Metalle und Materialien GmbH, Höfener Straße 45, 90431 Nuremberg, Germany
3Institute of Materials Research, Helmholtz-Zentrum Hereon, Max-Planck-Straße 1, 21502 Geesthacht, Germany*corresponding author

In order to seize new application areas for intermetallic γ-TiAl based alloys, an increased service
temperature and improved mechanical properties are a necessity. Considering that these alloys
consist mainly of γ-TiAl phase, strengthening of this phase is a crucial point to further advance
this class of materials. A promising alloying element meeting the requirements for effective solid
solution strengthening of the γ phase is Zr. While its beneficial effect on the mechanicalproperties is already known in the scientific community, a detailed study of its influence on thephase transformations in the relevant Al range is still missing. Consequently, the present work
investigates model alloys based on the Ti-(42-46)Al-(2-4)Zr (at.%) alloy system regarding theinfluence of Zr on the microstructure and phase transitions. Microstructural characterization
reveals a stabilization of the γ phase due to Zr in the microstructure, which consists
predominately of lamellar α2/γ colonies and a minor amount of globular γ phase after hot-isostaticpressing. The hardness of the material increases due to both solid solution strengthening andrefinement of the colonies’ lamellar spacing by Zr. The phase transformation behaviour and therelated impact of Zr are investigated by differential scanning calorimetry (DSC) as well as highenergy X-ray diffraction (HEXRD) utilizing synchrotron radiation. Especially, two different
types of in-situ HEXRD heating experiments are conducted to investigate, on the one hand, thesolid-solid transformations below the material’s solidus temperature, and, on the other hand, theliquid-solid transformations at higher temperatures. DSC and HEXRD experiments combinedwith complementary heat treatments clearly show that the Zr additions increase the thermal
stability range of the γ phase, e.g. see Fig. 1a. Furthermore, phase transformations involving theliquid phase are drastically shifted towards lower temperatures when alloying with Zr. Thus, theaddition of Zr effectively narrows the α phase field region as shown in Fig. 1b. Furthermore, thecombination of X-ray diffraction and ab-initio calculations based on density functional theory(DFT) grants valuable insights into the effect of Zr and Al on the lattice parameters of the γphase. More precisely, Zr is found to cause a strong reduction of the tetragonality of this phase
due to an elongation of the shorter unit cell axis a, while the longer axis c remains mostly
unaffected.

Figure 1. a) Phase fraction evolution of a Ti-46Al-2Zr and a Ti-46Al-4Zr (at.%) alloy; b) Quasibinary Ti-46Al-xZr phase diagram derived from the results of HEXRD, DSC and heat treatments.

38

Invited Talk
Additive Manufacturing of Gamma Titanium Aluminides: A Review
of Methods, Properties and Challenges
Marc Thomas1*
1

DMAS, ONERA – The French Aerospace Lab, Paris Saclay University, 92320 Châtillon, France*corresponding author

Additive Manufacturing (AM) of metallic parts has shown a growing interest in the last decade,especially in the aerospace industry for weight saving, functional design, lower buy-to-fly ratio
and rapid manufacturing with reduced lead time. Significant AM breakthroughs have alreadybeen reported for intermetallic alloys such as gamma titanium aluminides. Currently, γ-TiAlalloys have already been successfully processed via powder bed and powder feed technologies. In
particular, electron beam powder bed fusion (EB-PBF) and direct energy deposition (DED) arethose reported so far to successfully fabricate crack-free TiAl samples. EB-PBF is probably themost mature technology to produce sound TiAl components with a good geometrical precision
for aerospace and energy generation applications. DED coupled with machining steps canbecome attractive for restoring γ-TiAl alloys parts. Instead of replacing the entire part, repair
solutions using DED are more cost effective. Powder feed technology also offers interesting
perspectives by enabling the fabrication of functionally graded materials (FGMs) with gradualtransition microstructures. In addition, L-PBF as a powder bed technology can be emphasized asa more prospective method for producing crack-free TiAl samples.
These AM technologies are discussed in terms of processing challenges, by highlighting thedifferent methods in reducing and even preventing cracking susceptibility, such as preheating andpost-heating stages between layers, process optimisation. In the case of gamma aluminides,
because of the large variety of microstructures involved with the rapidly solidified condition, astrong process – microstructure – property relationship is observed. So, the different AM
technologies are also compared in terms of optimum process conditions, microstructure
characteristics, and related mechanical properties.
Finally, this review addresses novel technology and on-going effort of AM TiAl alloy
development. For instance, successful attempts are reported in the literature to combine
conventional casting or forging processes with DED by using similar or dissimilar TiAl alloys.
Some studies have also emerged on the R&D of in situ reactive synthesis from elemental
powders by using DED for Ti-Al alloys. Moreover, blending pre-alloyed TiAl powder and Si3N4
precursor has been used to prepare TiAl metal matrix composites from in situ reaction during the
AM process. The wire arc additive manufacturing (WAAM) process can also be highlighted tosuccessfully fabricate crack-free TiAl samples by using different elemental wire consumables.
Attention is also drawn to the properties and challenges associated with the chemical compositionof different AM TiAl alloys.
.

39Invited Talk
Production of intermetallic, spherical powders
Karin Ratschbacher1*
1

GfE Metals and Materials Gmbh, Hoefenerstrasse 45, Nuremberg, Germany*corresponding author

Introduction
The development of ultra-high temperature alloys has identified MoSiB, MoTiSi- and VSiB
alloys as promising candidates for future applications. They demonstrate high strength, highmelting points and intrinsic protection against oxidation [1-4]. Due to the high melting point andhigh strength, the materials need to be produced through a powder-metallurgical approach andproducts built through additive manufacturing. The production of spherical MoSiB, MoTiSi and
VSiB- Powders, needed for additive manufacturing, will be introduced in this article. The
powders have successfully been processed through additive manufacturing [5-7].
Materials and Methods
To produce the feedstock for the EIGA process, a powder metallurgical route was chosen.
Alloying elements were mixed and homogenized, to obtain the target compositions. The powders
were compacted and underwent a thermotreatment at a temperature below the exothermal peak,which was determined beforehand through DSC measurements. The dimensions of the EIGA
feedstock material were 65mm diameter for all materials, tested.

Results and Discussion
Stable process conditions could be obtained. The expected phases could be detected in the
powder particles, which points to a fully alloyed material. The obtained powders show goodflowability for particles 25-80µm, which makes them suitable for additive manufacturing.
References[1] P. Jain, K.S. Kumar, Dissolved Si in Mo and its effects on the properties of Mo–Si–B alloys, Scripta Materialia,
Volume 62, Issue 1, 2010, Pages 1-4, https://doi.org/10.1016/j.scriptamat.2009.09.008.
[2] M. Krüger et al., “Correlation between microstructure and properties of fi ne grained Mo-Mo3Si-Mo5SiB2
alloys,” Intermetallics, 2014, doi.org/10.1016/j.intermet.2013.10.025.
[3] P. Jéhanno, M. Heilmaier, H. Saage, M. Böning, H. Kestler, J. Freudenberger, S. Drawin, Assessment of the hightemperature deformation behavior of molybdenum silicide alloys, Materials Science and Engineering: A, Volume463, Issues 1–2, 2007, Pages 216-223, https://doi.org/10.1016/j.msea.2006.08.125.
[4] G. Hasemann, C. Müller, D. Grüner, E. Wessel, M. Krüger, Room temperature plastic deformability in V-rich V–
Si–B alloys, Acta Materialia, Volume 175, 2019, Pages 140-147, https://doi.org/10.1016/j.actamat.2019.06.007.
[5] J. Schmelzer, S.-K. Rittinghaus, A. Weisheit, M. Stobik, J. Paulus, K. Gruber, E. Wessel, C. Heinze, M. Krüger,Printability of gas atomized Mo-Si-B powders by laser metal deposition, International Journal of Refractory Metals
and Hard Materials, Volume 78, 2019, Pages 123-126, https://doi.org/10.1016/j.ijrmhm.2018.08.016.
[6] J.Schmelzer, S.-K. Rittinghaus, K. Gruber, P.Veit, A.Weisheit, M. Krüger, Printability and microstructural
evolution of a near-eutectic three-phase V-based alloy, Additive Manufacturing, Volume 34, 2020, 101208,
https://doi.org/10.1016/j.addma.2020.101208.
[7] Hinrichs, F., Kauffmann, A., Schliephake, D., Seils, S., Obert, S., Ratschbacher, K., ... & Heilmaier, M. (2021).
Flexible powder production for additive manufacturing of refractory metal-based alloys. Metals, 11(11), 1723.

40

Invited Talk
Development of the TiAl IRIS alloy by Spark Plasma Sintering

Alain Couret1*, Marc Thomas2 and Jean-Philippe Monchoux1
1.

CEMES, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, 31055 Toulouse, France
ONERA/DMAS, Université Paris-Saclay, 92322 Châtillon Cedex, France* Corresponding email: alain.couret@cemes.fr
2.

During the last fifteen years, the TiAl-IRIS alloy (Ti49,9Al48W2B0,1) has been developed in consistency
with the Spark Plasma Sintering (SPS) for structural applications at temperatures up to 800 °C inaeronautic and automotive engines. SPS is a consolidated powder metallurgy (PM) process where a
direct pulsed electric current of high intensity and an uniaxial pressure are simultaneously applied on agraphite assembly containing the powder. This presentation is divided into three parts.
The first part will be devoted to the SPS process. It will be shown how versatile SPS is to control andoptimise TiAl microstructures. The most critical issues, as the quality of the powder, the control of thealloy temperature and the sintering of up-scaled billets, will be addressed. The experimental method
used to sinter near-net-shape blades in a single SPS step will also be shown.
The aim of the second part is to describe the route to obtain alloys with improved properties, satisfying
the industrial requirements. The initial goal was to reach a good compromise between the creep
resistance at high temperature and the ductility at room temperature. This was successfully achieved
through the addition of boron and tungsten, and through the development of a resistant lamellar
microstructure with small colonies. The followed step by step procedure, which is based upon somebasic researches on the transformation mechanisms activated along the whole cycle and on themechanical properties, will be described in details. The mechanism of the microstructural evolution
during the SPS cycle will also be presented.
In the last part, the achieved properties of the SPS-IRIS alloy will be emphasised, i.e. ductility,
mechanical strength at various temperatures, creep, fatigue, structural stability and oxidation resistance.
The alloy behaviour will be correlated to the microstructural characteristics and to the deformation
mechanisms which are activated under various solicitations.
In the discussion section, the advantage of the spark plasma sintering process and the interest of tungsten
as alloying element will be underlined.

41

Invited Talk
Development of TiAl turbine blade with metal injection molding
process
Akira Fukushima1*, Kentaro Shindo2, Kosuke Ikeda2, Shintaro Sobu2,
Hiroshi Yamamoto1, Ichiro Miyoshi1, Tadayuki Hanada1
1

Mitsubishi Heavy Industries Aero Engines, Ltd.
2
Mitsubishi Heavy Industries, Ltd.
*corresponding author

Titanium aluminides (TiAl alloy) are attractive materials at intermediate high temperature becauseof its excellent specific strength. Therefore, TiAl alloy have been replaced Ni base superalloys in
the low-pressure turbine (LPT) of the state-of-the-art aircraft engines. The manufacturing processof TiAl turbine blade are mainly casting, forging or additive manufacturing. As more cost effective
manufacturing process for large quantity production is required, TiAl turbine blade with metal
injection molding process were developed.
The metal injection molding process consists of ingot production, powder production, feedstock
production, injection molding, debinding, sintering, and heat treatment. In order to manufacture
high quality blade, modeling and simulation of the injection molding and sintering process andoptimization of the heat treatment for microstructures were done. The simulation of the injection
molding results in control of filling, packing and powder distribution in the binder. The simulationof sintering process using actual alloy data results in control of deformation on the setter during
sintering. The microstructure optimization by heat treatment, developed by Takeyama et al, resultsin α2/γ lamellar microstructure with β/γ cellular microstructure of high strength and high fracture
toughness, regardless of high oxygen content. As a result, high quality, and precise blade of 200mm
can be manufactured with metal injection molding.
Fatigue properties of the developed LPT blade (Fig.1) were evaluated. The fatigue properties ofthe blade are the equivalent to those of small test specimens.
This work was supported by Council for Science, Technology
and Innovation (CSTI), Cross-ministerial Strategic Innovation
Promotion Program (SIP), “Material Integration” forrevolutionary design system of structural materials.

Fig.1 Developed LPT Blade42

Oral Presentation
FAST/SPS: NEW industrial post-process for full densification of 3D
TiAl complex shape from additive manufacturing
Arnaud Fregeac1*, Jennifer Mackie1, Yannick Beynet1, Romain Epherre1
1Norimat, 51 rue de l’innovation 31670 Labège*corresponding author

Norimat made an important industrial breakthrough by developing a unique and easy process
which enables the consolidation of 3D complex shapes by Spark Plasma Sintering (or Field
Assisted Sintering Technique). We have developed the hybridization between sinter based
additive manufacturing and SPS to fully densify (porosity <1%) Near Net Shape parts in only one
step and less than 1h of thermal treatment.
The conference will focus on the development of fully dense TiAl near net shape parts by
FAST/SPS. The recent results on the capability of the process opening the way to large scale
production and the improvement of multi-physics modeling to help users at each step (size andscale up) of the FAST/SPS process from conception to production.

Figure 1 : NNS fully densified TiAl blades just after SPS sintering

FAST/SPS is an efficient powder densification technique. It is used to sinter a wide variety ofmaterials (ceramics, metals, alloys, composites, etc.). Compared to conventional processes, itallows to reduce by 10 the production time while enhancing material performances. FAST/SPS is
at a turning point in its history, attracting much interest in recent years for multiple reasons:
1. Advanced industry is looking for new process to facilitate innovative material
development and manufacture.
2. FAST/SPS is an ecofriendly process without any greenhouse gaz emitted, having zeromaterial losses and low electric consumption.
3. High volume production is now achievable through mastering key process parameters
thanks to innovative numerical tools capable of optimizing the process from conception to
production. 3D complex shapes are now achievable using FAST/SPS, opening the way tothe manufacturing of Near Net Shape parts for all types of material (ceramics, metals,
composites, ...)

43

Oral Presentation
Application of MIM process to TiAl Turbine Blade
Tadayuki Hanada1*, Kentaro Shindo2, Shintaro Sobu2, Kenji Doi 3, Kazuki Hanami3
1

MITSUBISHI HEAVY INDUSTRIES AERO ENGINES, LTD
2
MITSUBISHI HEAVY INDUSTRIES, LTD
3
OSAKA YAKIN KOGYO Co., Ltd.
*corresponding author

Abstract
Titanium aluminides(TiAl) Turbine Blade is now introduced to Low Pressure Turbine(LPT) of
Aero Engine as a replacement of conventional Ni based super alloy because of its excellent material
properties in high temperature environment with lower density than that of conventional Ni based
super alloy. Current TiAl Turbine Blade in production is produced by machining from the raw
material of casting or forgings. Recently additive manufacturing(AM) technology is being
introduced to produce near net raw material of TiAl Turbine Blade. One of the reasons for thisintroduction of new manufacturing technology is that there are a few limited raw material suppliers
due to its manufacturing difficulties in casting or forging process related to chemical reaction
characteristics or low ductility. As one of other solutions to produce TiAl Turbine Blade, Metal
Injection Molding (MIM) process might be a potential option to produce near net shape raw
material because of its high flexibility in shape, material and high productivity for high volume
production.
This article describes overview of the past experimental trials in application of MIM process to
TiAl LPT Blade such as sintering process, material tests, component tests for the confirmation of
microstructure and material capability in strength, creep and fatigue using small scale TiAl Turbine
Blade and future challenges of large scale TiAl Turbine Blade produced by MIM process.

Fig.1 Small scale Turbine Blae

Fig.2 Dovetail Test

Fig.3 Spin Test

44

Invited Talk
Microstructural Heterogeneity and Post Processing Effects on Mechanical Properties of
Ti-48Al-2Cr-2Nb Additively Manufactured by Electron Beam Melting (EBM)
J. J. Lewandowski1, M. Seifi1,2, Ayman Salem3, Dan Satko3, and S.L. Semiatin3,4
1

Department of Materials Science and Engineering Case Western Reserve University, Cleveland, OH 44106, USA

2

ASTM International, Washington, D.C., USA

3

Materials Resources LLC, Dayton, OH, USA

2,3

Airforce Research Laboratory, Materials and Manufacturing Directorate, AFRL/RXCM, Wright-Patterson Air Force
Base, OH 45433, Dayton, OH, USA

Abstract:
Both cast and wrought titanium aluminide alloys have been studied for more than two decades
because of attractive properties that include low density, high specific strength, high specificstiffness and oxidation resistance up to about 700°C. Electron beam melting provides anotherprocessing approach to produce net shape components, although little work has been conducted to
examine processing-microstructure-property relationships. This work examines as-deposited γTiAl (Ti-48Al-2Cr-2Nb) specimens made by Arcam AB and post-processed materials. Mechanicalbehavior studies on as-deposited, HIPed, HIPed + HT conditions included Vickers micro-hardness,
compression, fracture toughness and fatigue crack growth testing. In addition, microstructuraldetails were investigated over a range of scales using various microscopy tools. The presentation
will summarize this evolving work on the characterization of AM γ TiAl and provide somecomparison to other conventional (e.g. as-cast, wrought) γ-TiAl alloys.

45Oral Presentation
Influence of some promising alloying elements on the mechanicalproperties and deformation mechanisms of TiAl based alloys
Benjamin Galy1, Alain Couret1, Guy Molénat1, Muriel Hantcherli1, Jean-Philippe Monchoux1,
Michael Musi2, Petra Spoerk-Erdely2, Helmut Clemens2, Louise Toualbi3, Marc Thomas3,
1

CEMES, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, 31055 Toulouse, France
Department of Materials Science, Montanuniversita t Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria
3
ONERA/DMAS, Université Paris Saclay, 29 Avenue de la Division Leclerc, BP 72, 92322 Châtillon Cedex, France
2*muriel.hantcherli@cemes.fr

The aerospace sector faces a significant challenge in reducing CO2 emissions, which calls
for the creation of novel functional materials that can withstand high temperatures. TiAlintermetallic alloys make suitable choices because of their low density and their good mechanicalresistance at high temperature. These alloys exhibit a maximum working temperature around
700°C and are used in low-pressure parts of turbine blades. One of the major issues consists inimprove their function temperatures of at least 800°C to be incorporated in higher pressure parts.
Three alloys which exhibit high potential for industrial applications at high temperatures havebeen developed with the addition of alloying elements: IRIS alloy (Ti49.92-Al48-W2-B0.08),
developed by CEMES and ONERA and TNM (Ti51.4-Al43.5-Nb4-Mo1-Bo0.1) / TNM+
(Ti50.7-Al44-Nb3.6-Mo1-C0.3-Si0.3-Bo0.1) alloys, developed by Leoben University. Thesedevelopments reveal that the incorporation of alloying elements such as tungsten, molybdenum,
carbon, and silicon, in the chemical composition of the TiAl alloys is an interesting way to
improve their resistance at higher temperature. However, these enhanced properties are not yet
well understood.
In this context a fundamental study has been carried out to better understand the effect ofeach element on the high temperature properties of TiAl with a particular interest in the role oftungsten. Thus, five model alloys with specific chemical composition (Ti48.4Al / Ti-48.7Al2.1Mo / Ti-46.3Al-2.2W / Ti-46.3Al-2.2W-0.2C / Ti-46.5Al-1.9W-0.3Si) were developed toisolate the specific effect of each element of the study. Elaboration was done by spark plasma
sintering from powders obtained by EIGA process. Tensile and creep tests were performed on the
different alloys with a lamellar microstructure to determine which alloy exhibits the best potential
for future industrial applications. Specimens of gamma microstructure of Ti48.4Al and Ti46.3Al-2.2W composition were deformed in creep at 800°C, on which post mortem and in situ
TEM observations have been carried out. These observations allowed to determine the active
deformation mechanisms, as well as their kinetics. In addition to these observations, atomic probe
experiments were conducted on the Ti-46.3Al-2.2W alloy to investigate the role of tungsten on
the properties of TiAl at the atomic scale.

46

Oral Presentation
High Temperature Oxidation of -TiAl Alloys: Effect of Zr
Alexander Donchev1*, Melissa Allen2, Michael Musi3, Petra Spörk-Erdely3, Helmut Clemens3,
Mathias Galetz1
1

DECHEMA‐ Forschungsinstitut, Theodor-Heuss-Allee 25, 60486 Frankfurt am Main/Germany
2
GfE Metalle und Materialien GmbH, Höfener Str. 45, 90431 Nuremberg/Germany
3
Department of Materials Science, Montanuniversität Leoben, Franz-Josef-Str. 18, 8700 Leoben/Austria*

Corresponding authorIntermetallic titanium aluminides based on the -TiAl phase (TiAl alloys) are candidates forseveral high temperature applications due to their high specific strength at elevatedtemperatures among other properties. TiAl alloys are already used as turbine blades in the laststages of the low-pressure turbine of jet engines. Their maximum operating temperature does
not exceed about 700°C for longer service times due to an insufficient oxidation resistanceand oxygen induced embrittlement. Alloying is one possibility to improve the oxidation
resistance of TiAl alloys. The study of alloying additions, e.g., with Nb is a major topic inresearch on TiAl alloys since many years. Several technical alloys possess a certain amount of
the β-stabilizing element Nb, e.g., the alloy Ti-48Al-2Nb-2Cr (TiAl 4822) used in the GEnX
engine. New developments led to the addition of Zr to increase the mechanical properties. Yet
it is unknown how Zr affects the oxidation behavior of -TiAl based alloys. Zr is known to
improve the oxidation behavior of alumina forming Fe- or Ni-based materials by the so-called
reactive element effect. Hence, different amounts of Zr (2, 4 and 8, all in at. %) were alloyed
to a binary alloy with the base composition Ti-46.5Al. The Al content was kept constant. Fora fourth alloy also Nb was added next to Zr (3 at.% Zr + 1 at.% Nb) and the effect of these
additions on the oxidation behavior at 900°C in air were studied. Isothermal and thermocyclic
exposure tests were performed and the results are discussed also in comparison to technicalalloys, e.g., the TNM and the TiAl 4822 alloy. All alloys form mixed oxide scales whichshow spallation, but the tendency of spallation differs. Figures 1a-d show SEM images of thethree Zr containing specimens and a TiAl 4822 sample after thermocyclic exposure (25 hcycle) at 900°C for 120 h in air. Alloying with 2 at. % Zr reduces the oxide scale thickness(Fig. 1b) compared to the binary alloy (Fig. 1a). The additional alloying with Nb further
improves the oxidation behavior without impeding mixed scale formation (Fig. 1c) whichcomes close to the thickness of the scale formed on the technical alloy TiAl 4822 already inservice (Fig. 1d).
a

b

c

d

Figures 1: SEM images taken in BSE contrast of the mixed scales formed on the surface of
the investigated alloys: (a) Ti-46.5Al, (b) Ti-46.5Al-2Zr, (c) Ti-46.5Al-3Zr-1Nb, and (d) TiAl
4822 after 5 cycles of oxidation (= 120 h) at 900°C in air. Note that the scale bar in Figs. (a)and (b) is 30 µm, while in Figs. (c) and (d) it is 10 µm.

47Oral Presentation
Effects of Various Factors on the Impact Resistance of TiAl Alloys
Toshimitsu Tetsui1*
1

National Institute for Material Science, Tsukuba 305-0047, Japan*Corresponding author

Despite the widespread use of TiAl alloys, their poor impact resistance has recently emerged
again as a major issue. Therefore, in this study, the effects of various factors on the impact
resistance of TiAl alloys were investigated. Cast and forged materials were used as test samples.
The investigated alloy composition were binary alloys, ternary alloys with varying amounts ofadditive elements, and various practical TiAl alloys including 4822 and TNM. Additionally, themicrostructure was changed by heat treatment. The evaluation method of impact resistance used
was the Charpy impact test with a small-capacity hammer using a non-notched test specimen, andthe test temperature ranged from room temperature to 1000 °C. Consequently, the following
findings were clarified: All TiAl alloys underwent brittle fracturing, even at high temperatures. Figure 1 shows asecondary electron image of the fractured surface of 4822 as a representative example.
 The Charpy absorbed energy of practical TiAl alloys was less than 1/20 at room temperatureand less than 1/8 at elevated temperatures compared to that of Inconel713C.
When comparing between TiAl alloys:
 The absorbed energy increased at Al concentrations of 46–47at%.
 As for the microstructure, fully lamellar was good, and the γ single phase and γ + β, which
do not contain the lamellar structure, exhibited significantly low impact resistance.
Moreover, the β phase reduced impact resistance at low and medium temperatures.
Therefore, cast alloys have better impact resistance than forged alloys.
 Additive elements that improved impact resistance were only Cr and V with appropriate
amount, and all the other elements reduced impact resistance compared to the binary alloy.
 Particularly, Nb, C, and Si, which are usually added to improve high-temperature properties,
significantly reduced impact resistance.
 The impact resistance of all practical TiAl alloys was significantly lower than that of thebinary alloys.
Based on the above-mentioned findings, it is questionable to add Nb to the TiAl alloys for lowtemperature applications, and considering the material cost together, a binary alloy or a ternary
alloy with Cr/V addition is sufficient.

Figure 1. Secondary electron images showing the fractured surfaces of 4822 tested by
Charpy impact tests at RT, 550 and 1000 °C.

48

Oral Presentation
Deformation twins in α2-Ti3Al phase
Lin Songa*, Fritz Appelb Florian Pyczakb, Tiebang ZhangaaState Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an,
Shaanxi 710072, Chinab

Institute of Materials Physics, Helmholtz-Zentrum Hereon, Max Planck-Str. 1, Geesthacht 21502,
Germany
Corresponding author: Lin Song, songlin@nwpu.edu.cn

Abstract
Compared to the disordered HCP metals, the α2-Ti3Al phase is reluctant to twin due to its D019
ordered structure. However, in a high Nb-containing TiAl alloy under high temperaturecompression, abundant deformation twins were observed in the α2 phase. The twinning modes
include {20 1}< 014> compression twin, {1 01}< 102> tension twin, three-fold internal twinsand double twins in various modes. Given the large shufflings and the atomic site interchanges
required for the operation of this twinning system, it is concluded that twinning of the α2 phase is adiffusive-displacive process. The details of the atomic processes of each type of twin are
elucidated by electron microscopy. In the compression twins, ωo phase nucleation was observed at
the twin interface. In the tension twins, the structure of interface is similar to those reported in thedisordered α phase, which is formed by prismatic (P) and (0001) basal (B) planes. The shear
mechanisms of the twins were discussed based on the observed morphology. The factors that
support the deformation twins in the α2 phase were summarized. Our results indicate that inmodern TiAl alloys deformation twins in the α2 phase could be an important mechanism at service
temperatures.

49

Key Note

An Overview on “Materials Integration” for Revolutionary
Design System of Structural Materials in SIP in Japan
Yoshinao Mishima1*, Masao Takeyama2
1

Prof. Emeritus, former President of Tokyo Institute of Technology, Tokyo, Japan
President of The Japan Agency for Medical Research and Development (AMED)

2

Department of Materials Science & Engineering, School of Materials and Chemical Technology,
Tokyo Institute of Technology, Tokyo, Japan*corresponding author

Cross-ministerial Strategic Innovation Promotion Program (SIP) is a national program led by
the Council for Science, Technology and Innovation（CSTI）of the Government of Japan, inorder to realize scientific and technological innovation to solve the most socially andeconomically important national issues. ‘Materials Integration for Revolutionary Design System
of Structural Materials’, one of the 12 subjects in the 2nd term of SIP, was conducted for 5 years
from FY2018 till FY2022.
To strengthen the global competitiveness of materials science and engineering of Japan,
materials integration (MI) systems have been developed which combine materials engineering
methods, experiments, theoretical computations, and data science to connect processing,structure, property, and performance on computers to accelerate R&D. In 5 years, 10.7 billion
JPY was invested, and around 800 researchers from 49 organizations (19 in industry, 25 inacademia and 5 in government) tackled the subject. As main R&D accomplishments, MI systems
called ‘MInt’ for structural metallic materials and ‘CoSMIC’ for carbon fiber reinforced plastics(CFRP), and MI systems for new materials such as intermetallic compounds and ceramic matrix
composites have been developed.
These systems contain inverse design functionality, which can form the conditions of materials
and manufacturing processes necessary to realize required performance. In the final fiscal year,
computational modules and databases were installed in these MI systems, verified and validated.
Regarding practical application, the final goal is to have our MI system be broadly utilized byindustry, academia and government to support their materials R&D.
One of the most remarkable accomplishments in this program is TiAl LPT blade manufactured
by MIM and AM processes. The newly designed blades are developed through a uniquelydeveloped inverse MI system, and they are verified to meet the required performance. You willknow how good they are in this workshop. We always welcome any of you to work together on
R&D of materials in the future.

50Oral Presentation

Lamella orientation control of β-Solidifying TNM Alloys
via High-Temperature Compression
M. Keïta1, 2, C. Solís1, Y. Zhang2, J-F Moulin1, W. Gan1, E. Bouzy2
1

GEMS at MLZ, Helmholtz-Zentrum Hereon, Germany
Laboratoire d'Etude des Microstructures et de Mécanique des Matériaux (LEM3), 7 Rue Félix Savart, 57070 Metz, France

2

The third generation β-solidifying TNM alloys with (α2+γ) lamellar microstructures have been
considered excellent candidates for modern turbine blades due to their low density, high specific strengthand stiffness, excellent creep resistance, and good corrosion resistance. It has been found that orienting
the γ lamellae to the direction of the load can significantly increase the mechanical properties of thealloys, making lamella orientation control (texturization) an interesting topic for property optimization[1].
In this study, high-temperature compression (with a dilatometer) was first achieved to texturize the alphaphase through optimization of compressive speed and strain. An optimum fiber texture for the alphaphase has been identified by combining EBSD analysis with an in-situ XRD synchrotron.
Moreover, experiments were performed to observe the effect of the strain rates, taking a high strain rateof 1 s-1 and low strain rate of 10-2 s-1 while keeping the other parameters constant (cooling rates,
externally applied load during cooling, total deformation, and temperature). A difference in behavior forthe true stress-strain curve has been highlighted corresponding to a different type of mechanisms ofdynamic recrystallization.
Our results show that the microstructure and texture of TiAl alloys can be effectively controlled, and it
seems that having a high deformation and a low strain rate should promote the uniform fiber texture.
Further analyses are needed to understand the mechanisms behind the observed texture evolution. Thesefindings have potential implications for optimizing the processing and performance of TiAl alloys.
[1] « Polysynthetic twinned TiAl single crystals for high-temperature applications » Chen etal. Nature Materials vol.15 August 201651

50 µmOral Presentation
Effect of Microstructure on Creep Properties of TiAl4822 Built bySelective Laser Melting
Kazuhiro Mizuta1*, Yuta Hijikata2, Kazuhiro Gokan1, Koji Kakehi2
1

AeroEdge Co., Ltd., 482-6, Teraokacho, Ashikaga, Tochigi, 329-4213, Japan
Department of Systems Design, Tokyo Metropolitan University, 1-1 Minamiosawa, Hachioji, Tokyo, 192-0397,
Japan

2

*corresponding author

Introduction
In this study, selective laser melting (SLM) with a new heating system and an inert gas control
unit was applied to Ti-48Al-2Cr-2Nb and investigated the effect of addition of yttrium and heat
treatment on creep properties at high temperature.
Experiments
An M290 (EOS GmbH Electro Optical Systems) with a high-temperature modification unit thatfeatures a cooling of the process chamber and an inert gas purification system was used to build
the sample. Microstructure was analyzed by scanning electron microscope (SEM). The creep test
was carried out with the condition of 750℃/200 MPa in air. Addition of 0.21 wt.% of yttrium andheat treatment at 1400℃ for 2 hours were applied to the TiAl4822 to control the microstructure.
Results and Discussions
Fig. 1(a) shows the microstructure of the as-built specimen. The microstructure of the SLM
specimens with yttrium was shown in Fig. 1 (b). It was found that the addition of yttrium
effectively contributed to the suppression of the growth of the grain size. Fig. 1 (c) is the
microstructure with both heat treatment and addition of yttrium. By applying both heat treatment
and addition of yttrium, small grains of lamellae were obtained. The pinning effect on the grain
growth contributed to the suppression of the movement of the grain boundary. Fig. 2 shows theresults of creep tests. Adoption of both heat treatment and yttrium was the most effective among
all the conditions to improve the creep rupture life. This is mainly because the appropriate grain
size of lamellar was formed by a combination of the addition of the yttrium and the heat
treatment.
40

(b)

10 mm

50 µm

(b)

(c)

(c)

Elongation, ε [%]

(a)

35

SLM As-built

30

SLM (with Y)
SLM (with Y+1400℃ /2 hours)

25
20

EBM As-built

300 mm

15
10
5
0
0

10 mm

25

50

75 100 125 150 175 200 225 250 275 300 325
Time, t [h]300 mmFig. 1 SEM images of the microstructure of SLM
specimens. (a) As-built SLM specimen. (b)Specimen with 0.21 wt.% of yttrium. (c) Specimen
with both the heat treatment and the addition of
yttrium.

Fig. 2. Comparison of the creep curves. Creeprupture life of the SLM specimen with both
addition of yttrium and the heat treatment was
improved by more than 200 % and was evenlonger than the conventional electron beam melting(EBM) specimen.

52

Invited Talk
Fatigue cracking in additively manufactured gamma-TiAl
Mauro Filippini1*
1

Politecnico di Milano, Dipartimento di Meccanica, Milano – Italy*corresponding author

As the aeroengine industry is constantly increasing its interest in exploiting the advantages
offered by lightweight intermetallic alloys based on titanium aluminides, improved materials
properties satisfying high demanding design requirements are needed, so that novel designs withenhanced levels of structural integrity would allow to further decrease the consumption of fossil
fuels and reduce the carbon footprint of long-haul flight.
In the last few years, additive manufacturing technologies have been used to effectively produce
gamma-TiAl alloys suitable for structural components.
In this work, the fatigue properties of different variants of γ-TiAl intermetallics, with slightly
different chemical compositions and microstructures, produced by (selective) Electron Beam
Melting (EBM) are presented. The fatigue properties of an enhanced Ti-48Al-2Nb-2Cr alloy, ahigh Nb containing and a Mo-containing TiAl alloys are compared with already establishedalloys, all produced by additive manufacturing by selective Electron Beam Melting (EBM), withthe aim of highlighting, when possible, the effect of the microstructure on the fatigue properties.
High-cycle fatigue experiments have been conducted in the fatigue crack growth threshold region
for examining how the local microstructure influences local damage accumulation processes.
Additionally, specific monotonic and cyclic loading experiments with sub-size samples have been
recently conducted for investigating the influence of the microstructure on the fatigue damage
accumulation process. This analysis provides insightful information on the role of theintermetallic phases on the fatigue behavior of gamma-TiAl alloys and, by allowing a comparison
between different heat treatments and resulting lamellar colonies size, permits to highlight the
influence of the position of grain boundaries and the orientation of the lamellae for the onset of
fatigue cracking. Finally, a handful of fatigue crack growth experiments with sub-size specimens
have been also conducted with the aim of highlighting the behavior of fatigue cracks in thethreshold region, with special focus to the contribution of shielding mechanisms in the nearthreshold regime. The analysis and comparisons of different microstructures and alloy
formulations presented here is aimed at providing information for the selection of the
microstructures suitable for designing against fatigue with gamma-TiAl intermetallics.

53

Oral Presentation
Plasticity and brittleness of the ordered o phasein a TNM-TiAl alloy
Guy Molénat a*, Benjamin Galy a, Michael Musi b, Louïse Toualbi c, Marc Thomas c, Helmut
Clemens b, Jean-Philippe Monchoux a, Alain Couret aa

CEMES, Université de Toulouse, CNRS, 29 rue Jeanne Marvig, BP 94347, 31055 Toulouse, France,
Department of Materials Science, Montanuniversität Leoben, Franz-Josef-Straße 18, 8700 Leoben, Austriac
ONERA/DMAS Université Paris Saclay, 29 Avenue de la Division Leclerc, BP 72, 92322 Châtillon Cedex, Franceb*corresponding author

In order to identify the reasons for the brittleness of a TNM-TiAl alloy (Ti51.05Al43.9Nb4Mo0.95B0.1
in at.%), the plastic deformation behaviour of the ordered o phase is investigated. The
corresponding powder was densified by Spark Plasma Sintering to produce a near lamellar
microstructure made of γ/α2 lamellar colonies surrounded by  and o grains. Then, the room
temperature tensile behaviour is studied by carrying out tensile tests and additional in-situ
straining experiments in a transmission electron microscope (TEM). The TNM alloy exhibits alimited ductility, with the fracture surface of test specimens showing cleavage facets alonglamellar interfaces. In addition, the o grains contain nano-precipitates of the o phase anddeform plastically by <111> superdislocations dissociated into two superpartial dislocations
separated by an antiphase boundary. These dislocations glide in {011} planes and are observed to
be localized into pile-ups, which is related to the o strengthening precipitation within the ograins. This localised hardening behaviour leads to stress concentration in grain boundaries whichis assumed to be responsible for delamination along lamellar interfaces in neighbouring lamellarcolonies.

Corresponding paper:
Intermetallics 151 (2022) 107653
https://doi.org/10.1016/j.intermet.2022.107653.

54

Oral Presentation
Embrittlement after high temperature exposure: overview of theliterature in view of new findings
Jonathan D.H. Paul1*, Dirk Matthiessen1, Michael Oehring1, Fritz Appel1, and Florian Pyczak1
1Helmholtz-Zentrum hereon GmbH, Institute of Materials Physics, Max-Planck-Straße 1, 21502 Geesthacht,
Germany.
* jonathan.paul@hereon.de

It is well known that TiAl alloys are embrittled on room temperature tensile testing after being
exposed to elevated temperatures, however the reason behind the phenomena is little understood.
This contribution will present new results from an investigation that has been performed on
exposed tensile test samples that were tested under liquid nitrogen. The findings present a newlight on the embrittlement phenomena and will be discussed in relation to the various TiAlembrittlement theories that have been presented in the literature.

55

Oral Presentation
Study of fatigue mechanisms at the microstructure level in TiAl
alloysLouise Toualbi1*, Anna Ask1, Pascale Kanouté1
1

ONERA – the French aerospace lab*corresponding author

With a view to lightening aeronautical structures and using aircraft engines at increasingly hightemperatures, research into titanium aluminide intermetallic alloys has increased in recent years,
leading to their introduction in the most recent civil jet engines.
These alloys are highy dependent on the thermal history due to the processing route of the alloy,
meaning that for the same chemical composition, different microstructures can be obtained,
resulting in a dispersion of mechanical properties. In order to be able to take this specificity into
account, studies have been carried out to propose a finite element analysis methodology that is able
to take into account the effect of the microstructure of TiAl parts subjected to mechanical loads.
This study is part of the development of a multi-scale fatigue life assessment tool for TiAlintermetallics and more specifically for the TiAl IRIS grade. The aim of this work is to understandthe link between TiAl alloys microstructures and their fatigue strengths.
The fatigue analysis at the microstructure scale is performed using Fatigue indicators (FIP) thatgive robust measures of the driving force for fatigue crack formation. Two types of potential cracks
relevant to the mechanisms observed in the material are considered here, volume fatigue
transgranular and surface crack formation. The criteria are applied in a post-processing step after a
set number of cycles of a semi-periodic synthetic crystalline aggregate. The simulations can bemade very efficient by taking advantage of the concept of structural zoom, where sub-domains ofa larger model can be studied with increased detail (taking into account the lamellar structure ofindividual grains for example). Pertinent FIP for transgranular volumetric crack propagation arethose that associate the crack direction with the plastic slip directions, for example a modified
Fatemi-Socie criterion. The surface rugosity that develops on a free surface during cyclic loading
can be estimated using the results from the crystal plasticity simulation. A criterion based on theslip activity on each individual slip system is proposed that provides both the amplitude of the
intrusions and extrusions as well as their direction. The results of these simulations are comparedwith experimental characterisations of these intrusion/extrusion phenomena, obtained in particularfrom SEM observations and quantified by means of AFM measurements (Figure 1).

Figure 1. SEM intrusion and extrusion on a TiAl IRIS specimen subjected to cyclic loading at 750°C. Focus on AFM
measurement on a lamellar extrusion, on an extrusion at grain boundary and on a lamellar colony.

56

Invited Talk
Microstructure Control of TiAl Alloys by Additive Manufacturing
Hiroyuki Y. Yasuda1*, Ken Cho1, Mitsuharu Todai2, Minoru Ueda3, Masao Takeyama4,
Takayoshi Nakano1
1

Osaka University, Osaka, Japan
Institute of Niihama National College of Technology, Ehime, Japan
3
Metal Technology Co. Ltd., Tokyo, Japan
4
Tokyo Institute of Technology, Tokyo, Japan2*corresponding author

Cylindrical rods of Ti-48Al-2Cr-2Nb alloys were additively manufactured by electron beam
powder bed fusion (EB-PBF), so that the angle () between the rods and the building direction is0, 45 and 90 deg. Microstructure and mechanical properties of the alloys depend strongly on thebuilding condition and . For instance, high energy densities lead to the formation of 2/lamellar structure while near- structure is formed at low energy densities. On the other hand, at
middle energy densities, unique layered structure composed of duplex-like region and equiaxed 
grains ( band) is formed. Temperature distribution near the melt pool and the layer-on-layer
process during EB-PBF are responsible for the formation of the layered structure. If tensile load
is applied parallel to the longitudinal direction of the cylindrical rods at room temperature, large
elongation above 2% can be obtained at  = 45 deg, while tensile elongation at  = 0 deg is lessthan 1%. This is because shear deformation preferentially takes place parallel to the soft  bands.
Moreover, tensile elongation at room temperature is dependent on the thickness of the  bands at
 = 45 deg. On the other hand, the plastic anisotropy depending on  becomes insignificant above
973 K. In addition, fatigue and creep properties of the additively manufactured alloys at 1023 K
are comparable to that of the cast alloys. Hot isostatic pressing (HIP) is favorable to eliminate
pores, while the layered structure is stable even after HIP at and below 1463 K. When large TiAl
turbine blades are fabricated by EB-PBF at constant process parameters, temperature distribution
during EB-PBF depends on the size and shape of the blade, which results in inhomogenous
microstructure. A scan strategy considering heat transfer around an electron beam enables us tofabricate TiAl turbine blades with homogenous layered structure. Additive manufacturing of TiAl
alloys containing the  phase was also examined. This study was supported by the CrossMinisterial Strategic Innovation Promotion Program (SIP) from the Japan Science andTechnology Agency (JST).

57

Invited Talk
A simulation-based approach for EBM additive manufacturing of γTiAl
Isak Elfstrom*, Anders Snis, Sven Johansson, Erik Granhed
GE Additive Arcam EBM Center of Excellence, Gothenburg, Sweden*corresponding author

Electron Beam Melting (EBM) is a metal powder bed additive manufacturing technology that has
a proven capability of producing advanced components in several “hard to weld” alloys, Avio
Aero - a GE Aerospace business uses EBM technology for production of γ-TiAl blades for the
low-pressure turbine of GE’s GE9X engine. The key benefits of using EBM are the vacuum
environment, the high process temperature, and the high-speed beam movements.
By combining these EBM unique benefits with recent developments in mesoscale melt poolmodelling and thermal simulations on the macroscale, new melting and heating strategies havebeen developed. The melt pool modeling results provide details of the melt pool dynamics andthe solidification rates of the material, leading to new melt strategies. The macroscale thermal
simulations are used for controlling the overall energy input and the temperature distribution on
the part level. Together, these new developments open up EBM for enhanced process control
during production, as well as detailed microstructure tailoring at the part level in the future58

Oral Presentation
Microstructure and Mechanical Properties of
Additively Manufactured containing TiAl Alloys
Ken Cho1, Hiroyuki Y. Yasuda1*, Masao Takeyama2, Takayoshi Nakano1
1

Osaka University, Osaka, JapanTokyo Institute of Technology, Tokyo, Japan2*corresponding author

Recently, electron beam powder bed fusion (EB-PBF) has attracted much attention to fabricate
difficult-to-process materials such as TiAl alloys since the process can build 3D objects withcomplex shape. In this study, rectangular rods of -containing TiAl alloys were prepared by EBPBF with various process conditions. The microstructure and mechanical properties of these rods
were investigated focusing on input energy density. We found that it is necessary to lower theenergy density to improve the dimensional accuracy of the rods. However, excessively low
energy density causes formation of defects due to a lack of fusion. This means that suitableprocess conditions should be selected for fabricating defect free samples with excellent
dimensional accuracy. We also found that the microstructure of the alloy fabricated by the EBPBF process varies drastically depending on the energy density. A uniform 2// mixed
structure containing an 2/ lamellar and a / dual-phase regions is formed at high energy
density conditions. On the other hand, a lower energy density leads to the formation of ultrafine
2/ lamellar grains with / cells discontinuously precipitated at the grain boundary. The
ultrafine 2/ lamellar grains are formed via massive  phase transformation induced by rapid
cooling under low energy density conditions. It is important to note that the ultrafine 2/lamellar grains and the / cells are effective in increasing strength and ductility of the alloys,
respectively. The alloys with optimum microstructure exhibit higher strength and larger ductility
at 1023 K, compared with the cast alloys.
This study was supported by the Council for Science, Technology and Innovation(CSTI), Crossministerial Strategic Innovation Promotion Program (SIP), “Materials integration for
revolutionary design system of structural materials”, Japan.

59

Invited Talk
Solid solution Strengthening of TiAl alloys with Zirconium,
mechanical properties
Melissa Allen1, Volker Güther1, Janny Lindemann2
1

GfE Metalle und Materialien GmbH, Höfener Straße 45, Nürnberg, Germany
2
GfE Fremat GmbH, Lessingstr. 41, 09599 Freiberg, Germany

Introduction
The objective of the work is to improve the high temperature mechanical properties of titanium
aluminide alloys by using Zirconium for solid solution strengthening. Zr is a rarely used alloying
element in titanium aluminides but has a high potential of influencing the high temperature
properties positively due to its large atomic radius compared to Ti and/or Al.
Materials and Methods
Materials manufacturing is based on single Vacuum Arc Remelting (VAR) using compacted
consumable electrodes. Resulting VAR ingot are being remelted and homogenized in an
Induction Skull Melter and centrifugally cast in steel molds [1]. Two different ternary alloys
containing 2 and 4 at% Zr and 46,5 at% Al each have been manufactured. Cast parts were subject
to HIP for closing remaining casting porosity. Different heat treatments (HT) for creating
appropriate microstructures have been applied. Chemical analyses have been carried out. The
microstructural analysis was done by metallography and SEM. The tensile tests were done understandard test conditions at room temperature, 300°C, 700 °C and 850°C. The creep tests were
performed with 150 MPa at 750°C and 850°C.
Results and Discussion
DSC measurements show that the content of Zr within the alloy has a strong influence on thephase transition temperatures as well as on the solidification path [2]. Adjusted heat treatments
had to be developed for each alloy for generating comparable lamellar microstructures.
The increase of Zr content improves the yield strength in all temperature ranges. The decrease ofstrength at high temperature above 700°C was determined to be significantly lower compared toState-of-the- industrial TiAl alloys such as TNM and TiAl48-2-2 indicating a very effective solid
solution strengthening capability of Zr in TiAl alloys.
The creep resistance could be improved at 750°C and 850°C compared to common TiAl alloys
like TNM alloys.
References[1] V. Güther, M. Allen, J. Klose, H. Clemens, Intermetallics. 2018, 103, 12-22.
[2] M. Musi, S. Kardos, L. Hatzenbichler, D. Holec, A. Stark, M. Allen, V. Güther, H. Clemens,
P. Spoerk-Erdely, Acta Materialia, 2022, 241, 118414.

60

Invited Talk
Development of Rapid Determination Technique of Molten TiAl
Alloys using X-ray Fluorescence
Tomohiro Nishimura1*, Yusuke Yamada1, Takayuki Yamazoe1, Chishu Ono1, Takeo Miyamura1,
Hitoshi Ishida1
1

Kobe Steel, Ltd.

1.Introduction
Since TiAl alloy is an active metal, melting techniques such as Cold Crucible Induction Melting(CCIM) have been developed, in which a solidifying shell is formed where the water-cooled copper
crucible and molten metal come into contact, thereby preventing oxygen and impurities fromentering the molten metal. On the other hand, changes in the solidifying shell may cause
fluctuations in molten metal concentration. In the melting process of a new concentration system,
it is difficult to accurately ascertain changes in the solidifying shell, which may lead toconcentration deviations.
In order to meet the growing demand for TiAl alloys used in aircraft engine components, highquality TiAl ingots must be produced at low cost. Therefore, if ingot scrapping can be reduced bycontrolling the concentration narrowing during melting, it will lead to the production of highquality ingots at low cost. The author's group has been developing a rapid determination techniqueusing X-ray fluorescence [1], but there were issues with the small number of N (the analysis
variation in the same Al concentration was unknown) and the accuracy of certified referencematerials and analytical curves. Therefore, the purpose of this study was to improve the accuracyof rapid determination technology and to verify the accuracy (N increase) through the preparationof high-precision certified reference materials and analytical curves.
2.Experiment
The target concentrations were Ti-(27.3, 29.3, 31.3, 33.3)Al-4.8Nb-2.55Cr (mass%). 16 samples
were used for the four Al concentrations. 20 kg of material was melted at CCIM and the molten
metal was collected (S-1). The Al concentration in the sample was then analyzed by X-ray
fluorescence analysis (XRF). The material was added to fill the difference between the analysis
result and the target concentration, and the sample
was taken again (S-2). The concentration of thecollected sample was then analyzed. As describedabove, loading and sampling were repeated until thetarget concentration was controlled.
3.Result and discussion
The analysis results of Al concentration wereshown in Figure 1. The horizontal axis was thetarget Al concentration and the vertical axis was
the analysis value of XRF. The upper and lower
dotted lines indicated the target Al concentration
range of ±0.2mass%, which shows that it waspossible to control all 16 samples to within±0.15mass% of the target Al concentration,
indicating that the Al concentration could be
Fig.1 Result of Al concentration using
controlled with high accuracy in the Al
rapid determination.
concentration range of 27mass% to 34mass%.
Acknowledgements
This study was supported by the Council for Science, Technology and Innovation (CSTI), Cross-ministerial Strategic Innovation
Promotion Program (SIP), “Materials integration for revolutionary design system of structural materials”, Japan.
References[1]Collected Abstracts of the 2021 Autumn Meeting of the Japan Inst. Metals and Materials, (2021) No. J1 (DVD)61

Invited Talk
Progress on Titanium Aluminides within the NEWTEAM EU
project
Sara Biamino1,3,4*, Manuela Galati2,3,4*, Cristian Ghibaudo1,3,4, Giovanni Rizza 2,3, Giulio
Marchese1,3,4, Reinhold Wartbichler5, Helmut Clemens5, Luca Iuliano2,3,4, Michele Coppola6,
Daniele Ugues1,3,4
1

Department of Applied Science and Technology (DISAT), Politecnico di Torino, Italy2
Department of Management and Production (DIGEP), Politecnico di Torino, Italy
3
Center of Integrated Additive Manufacturing (IAM@POLITO), Politecnico di Torino, Italy
4
INSTM, Consorzio Interuniversitario Nazionale per la Scienza e Tecnologia dei Materiali, Italy
5
Department of Materials Science, Montanuniversität Leoben, Austria
6
AvioAero, Italy*corresponding author

In order to follow the today's aero-engine market needs, the exploitation of high-performancematerials is required. Introducing advanced alloys capable of withstanding higher operating
temperatures and/or exhibiting higher performances at a given temperature is a never-ending
focus of materials research. Additionally, coupling the new materials with advanced
manufacturing systems, such as Additive Manufacturing (AM), will allow to produce complex
geometry components and reduce their overall buy-to-fly ratio.
Among AM processes, the Electron Beam Powder Bed Fusion (EB-PBF) has already proved to
be promising for processing intermetallic TiAl based alloys. However, considerable efforts arenecessary to understand the role of the process parameters to precisely control the process interms of residual porosity, Al loss and homogeneity of the microstructure, thus improving thematerial performances. Moreover, in the intermetallic TiAl based alloys produced by EB-PBF,
the state-of-art-alloy for the industrial application of components, such as low-pressure turbine
blades, is the Ti-48Al-2Cr-2Nb alloy.
The NEWTEAM project evaluated a modification of the chemical composition of the Ti-48Al2Cr-2Nb reference alloy to increase the room temperature ductility of the alloy and limit thepenalty in creep performances as much as possible. The post-processing, involving a Hot Isostatic
Pressing (HIP) and a subsequent Heat Treatment (HT), was tailored for these new chemicalcompositions, thus optimising the material’s microstructure. One of the two investigatedchemical compositions was of particular interest to the progress of the project.
Theoretical and experimental analysis has been combined with simulation tools to optimise theprocess parameters for EB-PBF production. Such a combined approach was conducted regarding
the influence of Al loss during the EB-PBF process on phase fraction and phase transition
temperatures.
The present work summarises the results obtained in the NEWTEAM project "Next gEnerationloW pressure TurbinE Airfoils by aM" funded by the EU's Horizon 2020 programme in theframework of Clean Sky 2.
This project has received funding from the Clean Sky 2 Joint Undertaking under the European
Union's Horizon 2020 research and innovation program under grant agreement No. 821274.

62

Invited Talk
Data to aid materials design and process optimization of Titanium
Aluminides
Anders Engström1*, Yang Yang1, Hai-Lin Chen1, Qing Chen1
1

Thermo-Calc Software AB, Solna, Sweden*anders@thermocalc.se

Alloys are complex systems where microstructure and properties depend on both processing
conditions and chemical composition. Such variations are not typically reflected in handbook
data and repositories that tend to be limited in the scope of materials covered (their compositions)or the temperature ranges (processing conditions) or lack of time dependence. As such, theengineering simulations which depend on these data are limited, especially for cases involving
novel materials or new processes and often it becomes necessary to go and measure the needed
data or live with the uncertainty.
The CALPHAD approach captures the composition and temperature dependence of properties, aswell as their temporal evolution, for industrial multicomponent alloys. As a result, data can becalculated for materials or conditions where there are gaps in the measured data. Additionally,
location specific properties can be predicted and optimized for a part, which means that
manufacturers will no longer be restricted to design minimums.
CALPHAD simulations can be used to complement compilations or repositories of measured
data, improve machine learning models, and can also be used as input into engineering codes that
require more reliable materials property data.
In this presentation we introduce the CALPHAD approach and exemplify how CALPHAD based
tools can be efficiently used to aid materials design and process optimization of Titanium
Aluminides.

63Oral Presentation
Cost-effective Vacuum induction melting of gamma TiAl and NiTi
alloy
Kui LIU1*, Xiaobing LI1, Kun QIAN1, Mengshu ZHANG1, Chen BO1
1

Jihua Laboratory, Foshan, Guangdong, 528200, China*liukui@jihualab.ac.cn

Due to the nature of TiAl and NiTi as the intermetallic compound, the requests on materials
composition and the materials soundness are outstanding high which is a very big challenge for
manufacturing such attractive materials. As the first procedure of material process, melting
directly determines the main element chemical composition precision and impurity level, thesereally affectsuch intermetallic compound properties. Basically, the melting technology for TiAl or NiTi
mostly are confined to vacuum arc remelting (VAR), plasma arc melting (PAM) as applied in thetitanium industry. But such melting process still exists their own shortcomings, as well as the costchallenges.
The present research was mainly focused on the vacuum induction melting (VIM) techniquedevelopment to explore the possibility that whether such cost-effective process can be applied for
melting the more reactive TiAl and NiTi alloys. The thermodynamic stable CaO refractory was
selected as the melting crucible. Firstly, the study on thermodynamics of calcium and oxygen in
molten TiAl and NiTi alloys was performed to clarify the equilibrium properties by melting
material in CaO crucible. Secondly, these two kinds of alloys were practically melted in CaO
crucible as the functions of superheating temperature and holding time. The results show that thecontamination can be minimized when the thermodynamic stable CaO crucible and proper
melting technique were adopted. The oxygen content of actual melting TiAl ingot can becontrolled below 700 ppm, and that of NiTi is below 250 ppm. The main element concentration
deviation can be successfully controlled within 0.2 wt% from different melting heats. We expect
this work can provide a strong basic data support for cost-effectively melting high performance
homogenized gamma TiAl and NiTi shape memory alloys.
Keywords: TiAl; NiTi; melting; vacuum induction melting (VIM); CaO crucible.

64Oral Presentation
Control of lamellar colony size in sintering process forinjection-molded TiAl alloys
Kenji Doi1, Kazuki Hanami1*, Yasuhiro Iwasa1, Noriyuki Nishi1, Akira Kujihashi1,
Shuntaro Terauchi1, Tadayuki Hanada2, Kentaro Shindo3, Shintaro Sobu3
1

Osaka Yakin Kogyo Co., Ltd., 2Mitsubishi Heavy Industries Aero Engines, Ltd.,3
Mitsubishi Heavy Industries, Ltd.
*corresponding author

Metal injection molding (MIM) is a manufacturing method that combines injection molding andsintering. It enables the near-net-shape mass production of metal parts with complex geometries.
Metal injection molded parts are densified by sintering, and the density of the sintered parts
significantly affects the mechanical properties. A high density of the sintered parts can beobtained by increasing the sintering temperature. However, in the sintering of titanium aluminide(TiAl) based alloy, the lamellar colony becomes coarse when the sintering temperature isincreased. If the lamellar colony size is large, a high creep strength can be obtained, although thefatigue strength is low. In order to obtain the desired mechanical properties, it is important tocontrol the lamellar colony size. In the present study, sintering experiments were conducted toobtain the desired density while suppressing coarsening of the lamellar colonies.
TiAl based alloy powder was mixed with a certain amount binder to obtain a feedstock. The
feedstock was injection molded into tensile specimens. After debinding by heating under areduced pressure condition, the specimens were sintered under various conditions. The obtained
specimens were evaluated through density measurements, microstructure observation and energy
dispersive spectroscopy (EDS).
It was revealed that the desired density of the sintered compacts can be obtained while
suppressing the coarsening of the lamellar colonies. It was also revealed that there is a sufficientpossibility that the lamellar colony size of the sintered parts can be controlled through thesintering conditions.

65

Invited Talk
How elaborate in situ experiments guide modern alloy development
Petra Spoerk-Erdely1*, Gloria Graf1, Michael Musi1, David Obersteiner1, David Holec1,
Peter Staron2, Andreas Stark2, Emad Maawad2, Helmut Clemens1
1

2

Department of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria.
Institute of Materials Physics, Helmholtz-Zentrum Hereon, Max-Planck-Straße 1, 21502 Geesthacht, Germany.
*corresponding authorIntermetallic titanium aluminide alloys based on the ordered γ-TiAl phase are promisingmaterials for lightweight high-temperature applications. In addition to their low density ofroughly 4 g·cm-3, their high specific Young’s modulus and strength even at elevatedtemperatures, and their good oxidation and burn resistance, especially their excellent creep
properties make these alloys a material of choice for challenging structural applications.
Following intensive research and development activities, γ-TiAl based alloys have recently
entered service in the automotive and aircraft engine industries, e.g. as low-pressure turbine
blades in environment-friendly jet engines, as engine valves in sports and racing cars, or as
turbocharger turbine wheels. In the course of the past decades, the development of these complex
multi-phase alloys has benefited greatly from the application of in situ synchrotron X-ray
techniques. Diffraction and scattering techniques (Fig. 1), in particular, have offered access to theatomic structure of the material and provided insights into a variety of microstructuralparameters. Advanced experimental setups, which are steadily refined, have even allowed the
exploration of elaborate manufacturing processes and yielded insights that have so far been
inaccessible by means of conventional methods. Here, a practical introduction and overview ofrecent progress in this field of research are provided. Current prospects at modern synchrotron
radiation sources will be illustrated by means of selected case studies pertaining to different
stages in the development of modern γ-TiAl based alloys (i.e., fundamental research,
manufacturing, and fine-tuning of properties for application). In this context, available setups forin situ high-energy X-ray diffraction and small-angle X-ray scattering experiments will be
discussed in terms of their advantages as well as their limitations.

Figure 1: Schematic setup of a (combined) high-energy X-ray diffraction (HEXRD) and small-angle X-ray
scattering (SAXS) experiment, exemplified patterns as recorded by means of the area detectors, and typicalapplication areas for HEXRD and SAXS in the field of alloy development.

66

Oral Presentation
Relaxation Mechanisms and Diffusion Processes in -TiAl
Intermetallics
Jose M. San Juan1*, Thomas Klein2,3, Helmut Clemens3, Maria L. Nó1
1

Dpt. Fisica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, Apdo 644, 48080-Bilbao,
Spain.
2
Austrian Institute of Technology, Lamprechtshausenerstraße 61, Postfach 26, 5282 Braunau am Inn, Ranshofen,
Austria.
3
Dpt. of Physical Metallurgy and Materials Testing, Montanuniversität Leoben, Roseggerstr. 12, 8700 Leoben,
Austria.
*corresponding author: jose.sanjuan@ehu.es

In the last decades there has been a growing interest in developing new intermetallic families,
which would we able to improve the specific performances of superalloys at high temperature.
The TNB (Ti-Al-Nb) and the TNM (Ti-Al-Nb-Mo) families were developed to fulfil the required
performances. In particular, the creep resistance should be improved and consequently the studyof the diffusion mechanisms and the associated relaxation processes becomes very useful to get a
deep understanding of the physics involved during creep. Mechanical spectroscopy, including themeasurement of the internal friction spectra and the dynamic modulus curves as a function oftemperature between 600 K and 1400 K allowed approaching the study of such processes.
Previous works on several -TiAl alloys show several relaxation processes associated with the Ti
diffusion in the 2 phase [1-3] and with the Al diffusion in the  phase [4], as well as an internal
friction background at high temperature, which is associated with the creep behaviour [2]. At
present, new generation of -TiAl, called TNM+, is being developed to improve the creep
resistance by microalloying with C and Si [5]. However, Nb and C atoms in solid solution could
have a secondary effect on creep resistance by slowing down the diffusion of Ti in theconstitutive phases.
The aim of the present work is to overview the relaxation processes associated with Ti diffusionin 2 phase, which have been observed in several alloys with different amounts of Nb and C insolid solution, in order to evaluate their potential influence on such relaxation processes; theinfluence on Al diffusion will be also analysed. In addition, the relaxation processes observed byinternal friction are related, through the activation parameters, to the diffusion coefficients of thedifferent atomic species and compared with those from the literature. This comparison allows to
obtain a plot of the diffusion coefficients of Ti and Al in -TiAl, expanded towards thetemperature range close to the temperatures used in service conditions.
[1] J. San Juan, P. Simas, T. Schmoelzer, H. Clemens, S. Mayer, M.L. Nó, Acta Mater. 65, 2014, 338.
[2] M. Castillo-Rodriguez, M.L. Nó, J.A. Jimenez, O. Ruano, J. San Juan, Acta Mater. 103, 2016, 46.
[3] J. Ibáñez-Pérez, M.L. Nó, M. Oehring, H. Clemens, J. San Juan, J. Alloys & Comp. 867, 2021,
158880.
[4] L. Usategui, T. Klein, M.L. Nó, S. Mayer, H. Clemens, J. San Juan, Acta Mater. 200, 2020, 442.
[5] T. Klein, L. Usategui, B. Rashkova, M.L. Nó, J. San Juan, H. Clemens, S. Mayer, Acta Mater. 128,
2017, 440.

67

Oral Presentation
Microstructure and elastic properties in Ti-42Al-8.5Nb after longterm annealing at 550°C
Heike Gabrisch1*, Michaela Janosvká2, Marcus Willi Rackel1, Florian Pyzcak1, Andreas Stark1
1

2

Helmholtz-Zentrum Hereon, Geesthacht, Germany
The Czech Academy of Sciences, Prague, Czech Republic*corresponding author

Titanium aluminides are often alloyed with beta stabilizing elements for enhanced creep strengthand corrosion resistance. As a side effect, the addition of a third element to a binary alloy entails
the formation of a new phase in its microstructure.
In the alloy Ti-42Al-8.5Nb, the orthorhombic O-phase forms besides the 2 phase and  phasethat exist in binary Ti-42Al alloys. The O-phase forms from the 2 parent phase in thetemperature range between 450 and 650°C and it is stable between room temperature and 700°C[1]. During annealing, the shape, composition and relative volume fractions of the 2-phase andO-phase continuously change over time.
In this presentation, we investigate how the ongoing microstructural changes affect themechanical properties of the alloy. Using Transmission Electron Microscopy we monitor theevolution of the microstructure within 2 lamellae of lamellar (2 +) colonies during annealingat 550°C for up to 5000 h. This is complemented by in-situ Resonant-Ultrasound-Spectroscopy
measurements of the elastic moduli during annealing of separate samples at 550°C for 672 h.
The results show a continuous increase of the alloy’s overall elastic moduli. Thereby, a displacivetransformation at the beginning of the annealing experiment has a much stronger impact onelastic moduli than the subsequent diffusion assisted phase separation into 2 and O-phase during
the remaining annealing time [2].

References :[1]
Rackel et. al, Acta Materialia, (2016) 121: 343-351.
[2]
Gabrisch et al., Journal of Alloys and Compounds 932C (2023) 167578.

68

Oral Presentation
The Role that Hot Deformation Plays in Determining the Static andDynamic Mechanical Behavior of a High Niobium Containing γTiAl Alloy at Elevated Temperature
Yuzheng Zhang1*, Al Sommer1
1

Del West Engineering, USA*Corresponding author

The elevated temperature fatigue behavior of a high Nb containing γ-TiAl alloy is related to thedegree of metal working the billet receives during extrusion. In this study, we conducted highcycle fatigue tests on a γ-TiAl alloy containing 6 at% Nb at 450°C and 815°C. Prior to fatigue
testing, the Ti-Al ingots were hot extruded at various extrusion ratios. We found the fatigue life
was noticeably improved as we increased the extrusion ratio from 10:1 to 25:1. As-extruded
billets featured a fully lamellar microstructure. Metallographic analysis showed no discernible
difference in lamellae spacing and colony size. Fracture surface of the fatigue samples wasinspected to help understand the fracture behavior of the highly strained γ-TiAl alloy. The
improvement of fatigue life at elevated temperature is likely attributed to more intensive metal
work as extrusion ratio was increased. Fatigue life improvement is found to be more profound at
450°C than 815°C. This is evidence showing the improved fatigue strength is likely a result ofwork hardening. As fatigue test temperature increases, the material recovers from work
hardening. Another possible reason for improved fatigue life is the complete closure of cast voids
at high extrusion ratio. Tensile tests were also conducted at 450°C and 815°C at various extrusion
ratios. We found both the yield strength and ultimate tensile stress were improved as we
increased the extrusion ratio from 10:1 to 25:1. In conclusion, increasing extrusion ratio is proved
to be an effective way to improve the fatigue and tensile properties of the high Nb containing γTiAl alloy.

69

Oral Presentation
Thermal stability in microstructure of Mn containing β-solidifying γTiAl alloy
Xiaobing LI1*, Junjie HAO1, Peng XUE1, Chen BO1, Kui LIU1
1

Jihua Laboratory, Foshan, Guangdong, 528200, China*lixb@jihualab.ac.cn

Advanced intermetallic β-solidifying γ-TiAl based alloys with low density, good hot workability
and high speciﬁc strength/modulus, are known as promising candidates for aerospace andautomobile industries. However, the existence of large amount β stabilizing elements, such as Mo,
Cr, Nb Mn, in these alloys will make the ordered β phase (B2/βo) retain in the room temperature
with the volume fraction even above 20 vol.%. The retained B2 phase is generally quite
detrimental to the ambient or elevated mechanical properties due to its brittlement characteristic
at room temperature and easily decomposition tendency into some harmful precipitates at service
temperature(700~900°C). Meanwhile, the α2/γ lamellar structure is also proved to be
thermodynamically unstable due to the metastable α2 lamellae and the large thermal expansion
difference of α2 and γ, and the type of lamellar decomposition reaction will largely depend on thealloy composition. In this study, we choose a typical low-cost β-solidifying γ-TiAl based alloy
with the composition of Ti-42Al-5Mn (at.%) whose volume fraction of retained B2 phase isabout 20 vol.% for the as-casted microstructure. The phase evolution behaviors of the retained B2
at the temperature range of 650-950°C were systematically investigated. The transformation
types and the composition and structure were clarified with X-ray diffraction (XRD), electronprobe micro analyzer (EPMA), advanced electron backscatter diffraction (EBSD), transmission
electron microscope (TEM). The effects and mechanisms of Fe, Zr, Nb, W, Mo additions on thethermal stability and tailored of the retained B2 in the Ti-42Al-5Mn alloy were further studied.
And on this basis, we invented a novel alloy with the nominal composition of Ti-44Al-3Mn0.8Mo-0.1B-0.1C (named TMM), which can be forged or rolled directly from the ingot without
the pre-forging and near-isothermal canned conditions and whose B2 phase is thermodynamicallystable even exposure at 800°C for 3000h. Finally, the lamellar decomposition reactions and theeffects of Ta, Hf additions on its the thermal stability of TMM alloy were investigated duringexposure at 750~800°C. We expect this work will provide a strong technical support to optimize
the microstructure of the low cost containing β-solidifying γ-TiAl alloy, and to provide
fundamental data, knowledge and information (DKI) for the advanced intermetallic β-solidifying
γ-TiAl based alloys development.
Key words: Titanium aluminides; β-solidifying; B2/βo; lamellar structure; phase transformation;
microstructural evolution.

70

Invited Talk
Oxidation Behavior of TiAl Alloys, its Influence on the Mechanical
Properties and Mitigation Strategies via Coatings
L. Mengis1, C. Oskay1, A. S. Ulrich1, A. Donchev1, P. Watermeyer2,
C. H. Liebscher2, M.C. Galetz1*
1

2

DECHEMA-Forschungsinstitut, Theodor-Heuss-Allee 25, 60486, Frankfurt/Main, Germany
Max-Planck-Institut für Eisenforschung GmbH, Max-Planck-Straße 1, 40237, Düsseldorf, Germany*corresponding author

Two representatives of the intermetallic γ–based TiAl alloys, namely the GE 4822 as well as the
TNM-B1 alloy, have already found application in the LPT section of today´s aero engines. Theircurrent service temperature is limited to 700-750°C, above that temperature range an
unprotective mixed oxide scale grows too fast, that consists of TiO2 and Al2O3. However,oxidation below 700°C can already affect the mechanical properties of TiAl negatively althoughmass gains are very low in this temperature range. Since most existing studies investigate theoxidation behavior of TiAl at temperatures well above the current service temperature,comparative isothermal (600-900°C, dry air) and cyclic exposures (700°C, dry/wet air) of the GE
4822 and TNM-B1 alloys have been conducted for up to 1000 h. Four-point-bending tests at
room-temperature revealed a successive decrease in the fracture strain values with increasing
temperature and duration of exposure for both alloys. Emphasis was placed on the differentoxide scale morphologies as well as the microstructural degradation of the subsurface zone
which already appeared at 700°C (Fig. 1). Not only the existence of an oxygen-enriched Aldepleted layer at the interface between the oxide scale and the substrate seems to affect themechanical properties of the alloys, but also the increase of the α2 phase at the expense of theβ–phase that decomposes in the subsurface zone. Finally coating strategies are compared anddiscussed to suppress or delay the detrimental subsurface degradation.

Fig. 1: BSE image of the GE 4822 alloy (HIPed condition) after isothermal oxidation for 500 h
at 700°C in dry air.
.

71

Oral Presentation
Deposition of Ti2AlC MAX-phase based coating on
Titaniumaluminides to improve the oxidation resistanceNadine Laska1*, Radoslaw Swadzba2, Oliver Helle112German Aerospace Center, Linder Hoehe, 51147 Cologne, Germany
Lukasiewicz Research Network - Upper Silesian Institute of Technology, Gliwice, Poland*Nadine.laska@dlr.deCurrently, the application of intermetallic γ-TiAl alloys is limited by their deterioration instrength and creep resistance at elevated temperatures as well as by reduced oxidation resistanceabove 800 °C. The deposition of protective coatings is a promising opportunity to enhance theoxidation resistance by several orders of magnitude. Moreover, additive manufacturing processes
have enabled the production of components with more complex geometries. Thus, a design ofturbine blades made of γ-TiAl with internal cooling will be feasible in the near future. In thiscontext, the deposition of thermal barrier coatings and, therefore, protective bond coatings
become important.
MAX-phases are of increasing interest as material for high temperature applications due to theirunique combination of metallic and ceramic properties. Especially the alumina forming MAX
phases Cr2AlC, Ti2AlC or Ti2AlN are promising as oxidation resistant coatings. Unfortunately,
degradation of MAX phases is observed when applied on various Ti- or Ni-based alloys due tointerdiffusion processes between coating and alloy resulting in Al-depletion of the coating. Thisdegradation is not present when MAX-phases are applied on the Al-rich γ-TiAl based alloys,
which leads to a diffusion of Al from the substrate alloy into the coating and thus to astabilization of the thermally grown alumina layer. Moreover, MAX-phases are known as aductile material and could therefore prevent the deterioration of the mechanical properties
especially the fatigue behavior of such coated components in contrast to the common
intermetallic, protective but brittle coatings on γ-TiAl alloys.
In the present work, a Ti2AlC MAX-phase based coating was deposited by DC magnetron
sputtering. Using three pure elemental target materials of Ti, Al and C and a two-fold sample
rotation a homogenous all-around coating with a coating thickness of 10 µm. was applied on the
γ-TiAl alloy TiAl48-2-2. After the deposition process, the stoichiometric Ti2AlC coating was Xray amorphous. Therefore, a post-heat treatment at 800°C for 1 h was performed to achieve thedesired hexagonal MAX-Phase. Finally, the MAX-phase coated TiAl48-2-2 alloy was subjected
to cyclic oxidation tests at 850°C in laboratory air for up to 100 1 h-cycles.
The Ti2AlC MAX-phase coated TiAl48-2-2 alloy exhibits an excellent oxidation behavior at
850°C, due to the formation of a thermally grown alumina top layer. The phase formations during
the heat treatment were analysed by HT-XRD measurements indicating a homogenous coating
microstructure of the hexagonal Ti2AlC phase below an α-Al2O3 oxide layer. The interface
reaction zones between the coating and the TGO, as well as between the coating and the TiAl482-2 substrate alloy were analyzed by SEM with EDS and especially by high-resolution STEM.

72

Oral Presentation
Influence of oxidation protective coatings on the high temperature
fatigue behaviour of Ti-48Al-2Cr-2Nb
Christoph Breuner1*, Stefan Guth1, Radosław Swadźba2, Peter-Philipp Bauer3
1

Karlsruhe Institute of Technology, Institute for Applied Materials, Engelbert-Arnold-Strasse 4, 76131, Karlsruhe,
Germany2Łukasiewicz Research Network - Institute for Ferrous Metallurgy, K. Miarki 12 -14, 44-100, Gliwice, Poland
3
German Aerospace Center e. V. (DLR), Institute of Materials Research, Linder Hoehe, 51147, Cologne, Germany*corresponding author

With their excellent weight-specific properties and good oxidation resistance, intermetallic
Titanium Aluminides are suitable candidates to replace heavier nickel based super alloys in hightemperature applications. Ti-48Al-2Cr-2Nb is one promising example, which is already in use forlow-pressure turbine blades. While its duplex microstructure is stable up to 850 °C, the oxidation
resistance drastically decreases between 650 °C and 750 °C. Hence, oxidation protective coatingsmust be applied to further increase the application temperature. However, these coatings aremostly brittle, which may promote fatigue crack initiation and therefore reduce the fatigue
lifetime. To investigate the influence of oxidation protective coatings on the high temperature
fatigue behavior of 48-2-2, uncoated, pre-oxidized and coated plus pre-oxidized samples were
push-pull cycled under stress control at 750 °C. A TiCrAlY and a TiCrAlYSi coating wereapplied via Magnetron Sputtering and Closed Hollow Cathod - Physical Vapour Desposition
respective. The pre-oxidation was conducted in air at 850 °C for 300 h. The results show that at
higher stress amplitudes, pre-oxidized as well as coated and pre-oxidized samples fail early. Withdecreasing stress amplitude, in a narrow transition of about 15 MPa, the lifetime of coatedsamples increases drastically. When the stress amplitude is in the range of the fatigue strength,
both coatings as well as pre-oxidizing had only a minor influence on the fatigue lifetime. The
fatigue behavior of the different sample types is discussed based on damage observations and theimplications for service application of the coatings are analyzed.

73Oral Presentation
Development of Microstructure Factor-based
Mechanical-property Prediction Module for TiAl Alloys
Ryosuke Yamagata1*, Hirotoyo Nakashima1, Masao Takeyama1
1

Department of Materials Science and Engineering, School of Materials and Chemical Technology,
Tokyo Institute of Technology, Tokyo, Japan*corresponding author

A mechanical properties prediction module (MPM) for TiAl alloys has been developed as a partof an integrated computational inverse problem approach to accelerate the development of TiAllow pressure turbine blade in jet engines and reduce the extensive experimental efforts. The input
into this module is specific values of the properties required by industries, say, tensile strength(UTS) and fracture toughness (KIC). Then the output is a concrete value, such as volume fractionof the microstructural constituent governing the property. In order to get great performance out of
this module, the relationship database (DB) between microstructure and mechanical properties
and calculation model that describe mechanical properties as a function of microstructure factor
are needed. Therefore, this presentation exhibit how these DB and model have been constructed.
The construction of DB was carried out using a model alloy that is uniquely-designed ourselves.
Heat treatments were conducted for this alloy at given temperatures and time based on our
sophisticated phase diagram knowledge for microstructure control. Here, there are two important
microstructural constituents in the alloys: one is the lamellar microstructure consisting of α2Ti3Aland γ-TiAl phases and the other the cellular microstructure consisting of β-Ti and γ phases,
since we revealed the introduction of the cellular microstructure is effective in increasing themechanical properties. Then, volume fraction of this β/γ cellular microstructure (Vc) was
quantitatively analyzed from back-scattered electron images took from a scanning electron
microscope by an image analysis software. Mechanical properties were evaluated byconventional tensile and three-point bending test using round-bar shape and chevron-notched bar
specimens, respectively.
The calculation models were developed as follows:
d
α /γ
α /γ
T
T
T
T
c
c
d c
α /γ

α /γ

α

i

c

These models are characterized by these can be described using the terms of the properties of α2/γ
lamellar microstructure and deviation from it, that is the effect of introduction of β/γ cellular
microstructure. By using these models, UTS and KIC. can be predicted have a margin of error of±5% in UTS and ±20% in KIC. Therefore, the volume fraction of the microstructure constituent
to meet the required properties can be calculated as an output value of this module, then, it will
become an input value into microstructure design module for calculation of the alloy compositionand heat treatment conditions for meet satisfy the required properties.
This work was supported by Council for Science, Technology and Innovation (CSTI), Crossministerial Strategic nnovation Promotion Program ( P), “Material ntegration” forrevolutionary design system of structural materials.

74

Abstracts
Posters(in alphabetical order of the personpresenting it)

75

76

PosterMorphology and formation mechanism of titanium boride in Ti-45Al-2Mn2Nb-xB
Ruxin Cao1, 2, Renci Liu1, 2, Yuyou Cui1, 2, Rui Yang1, 2

Abstract
γ-TiAl alloys have attracted much attention for their high specific strength andgood mechanical properties at elevated temperature. Boron is added to refine
the lamellar grain size, which is believed to improve the poor room temperatureductility of TiAl alloys. However, it may degenerate the mechanical properties
due to the formation of borides with curvy morphology and large size, which areseverely influenced by the alloy composition and processing parameters. The
morphology and crystal structure of borides in Ti-45Al-2Mn-2Nb-xB (at.%)alloys containing different amount of B have been investigated to reveal the
relationship between B content and boride formation. In alloys containing 0.25
at.% and 0.5 at.% B, boride particles are curved and flake-like, and are
distributed at β dendrite boundaries, resulting from late nucleation andconstrained by matrix during growth. Curved, ribbon-like boride particles areobserved to randomly distribute in alloy containing 0.75 at.% B, and insufficientbehind-time supply of B atoms to the growth front is believed to be responsible
for their irregularity and large curvature bending and branching. In alloys
containing 1.0 at.% or higher B, straight needle/rod-like boride particles
dominate, and a small number of blocky particles appear in alloys containing
1.25 at.% and 1.5 at.% B. Most boride particles are of C32-TiB2 and have theirmajor axes along [0001] or [12̅ 10] in all alloys studied in this work, and Bf-TiB
and D7b-Ti3B4 randomly appear in conjunction with C32-TiB2 to form
intergrowths, while B27-TiB particles are free standing and only appear in alloys
containing 1 at.% or higher B.
Keywords: γ-TiAl, borides, solidification, formation mechanism, morphology

Contact:
Submitter(one of the authors):Ruxin Cao
Affiliation:
Email: rxcao20b@imr.ac.cn

77PosterOn the phase transformation sequence during rapid solidificationand cooling in the Ti-48Al-2Cr-2Nb alloy
Gloria Graf1*, Jan Rosigkeit2, Peter Staron2, Manuel Schemmel3, Thomas Antretter3,
Helmut Clemens1, Petra Spoerk-Erdely1
12

Department of Materials Science, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria.
Institute of Materials Physics, Helmholtz-Zentrum Hereon, Max-Planck-Straße 1, 21502 Geesthacht, Germany.
3
Institute of Mechanics, Montanuniversität Leoben, Franz Josef-Straße 18, 8700 Leoben, Austria.
*corresponding author

In recent years, additive manufacturing has emerged as a useful alternative to conventional
manufacturing techniques due to its numerous benefits, e.g. the generation of near-net-shape partsor the implementation of complex structures such as cooling channels [1,2]. Consequently, theprocess is considered for the production of turbine blades made of intermetallic γ-TiAl based
alloys. At the moment, research is focused on two major methods – electron beam melting andlaser powder bed fusion [1,2]. Using these techniques, high cooling rates are applied, leading toout-of-equilibrium phase transformations upon solidification and cooling. Due to the inherent
heat treatment during additive manufacturing, the original solidification microstructure is,however, oftentimes not apparent after the process and thus not well studied yet. The focus of thiswork is, hence, to explore the solidification pathway and the phase transitions that occur uponcooling in the Ti-48Al-2Cr-2Nb (at.%) alloy via in situ high-energy X-ray diffraction (HEXRD)
at a synchrotron facility. For the experiment a small experimental powder bed system was
employed [3]. However, in this case, the powder bed was replaced by a thin platelet, which was
single-track fused along the upper edge with a laser [3,4]. In this way, the disturbing influence ofsolid-phase signal generated by non-fused powder particles on the diffraction patterns was
avoided. An exemplified result of such an experiment conducted with a detector frame rate of
250 Hz is given in Fig. 1. From the stacking of the azimuthally integrated diffraction patterns
along the time axis of the experiment, the primary solidification phase could in this case beclearly identified as β, see Fig. 1. This experiment was corroborated by microstructural studies aswell as finite element analysis.

Figure 1: Phase evolution during laser fusion experiment determined by means of in situ HEXRD(β: β-Ti(Al); : -TiAl; /2: -Ti(Al)/-Ti3Al).
References[1] T.C. Dzogbewu, Manufacturing Rev. 7 (2020) 35.
[2] M. Thomas, T. Malot, P. Aubry, C. Colin, T. Vilaro, P. Bertrand, Mater. High Temp. 33 (2016) 571–577.
[3] E. Krohmer, F. Schmeiser, B. Wahlmann, J. Rosigkeit, G. Graf, P. Spoerk-Erdely, H. Clemens, P. Staron, C.
Körner, W. Reimers, E. Uhlmann, Rev. Sci. Instrum. 93 (2022) 65104.
[4] G. Graf, J. Rosigkeit, E. Krohmer, P. Staron, R. Krenn, H. Clemens, P. Spoerk-Erdely, Adv. Eng. Mater. 19(2021) 2100557.

78

Poster

Fatigue Crack Growth Behavior of TiAl Based Alloys based on
Compact Tension Test at Elevated Temperatures
Ryuichi Isomura1*, Ryosuke Yamagata2, Hirotoyo Nakashima1, Masao Takeyama1*
1

graduate student

Department of Materials Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan2
Department of Mechanical Engineering, Chiba University, Chiba, Japan2

correspondions author

Our previous study on fatigue crack growth (FCG) behavior of wrought TiAl alloys using
compact tension (CT) test at room temperature (RT) revealed that the introduction of bcc b-Ti
phase along the a2/g lamellar colony grain boundaries toughens the materials, that is, increasing
the stress intensity factor threshold (ΔKth) and reducing Paris slope m (crack growth rate: da/dN),
superior to those of the conventional alloys (L. Signori et. al, Intermetallics, vol. 100 (2018), pp.
77-87). In this study, thus, the FCG behavior at elevated temperatures was examined in air and Ar
atmosphere, in order to understand the underlying principle of crack initiation/propagation
mechanisms of the alloys. The microstructure of the specimens is similar to the previous ones
with b phase along the lamellar boundaries. The b phase was introduced using the cellular
reaction (α2+γ→β+γ) through multi-step heat treatments. A pre-crack was first introduced to eachCT specimen at RT, and FCG tests were done at RT, 873 K and 1073 K under 20 Hz with atension/tension load ratio R=0.1. The elevated-temperature tests were conducted in a uniquely
designed environment-controllable chamber with heating elements. In case of the tests in Ar, thechamber was evacuated and backfilled with Ar flowing. Crack length was measured by DCPD
(direct current potential drop) method.
The ΔKth obviously decreases at 873 K in both atmospheres. However, it goes up to the samevalue or even better at 1073 K in air whereas it stays low in case of Ar atmosphere. The m value
is nearly the same, regardless of the test conditions, but the da/dN value becomes apparently low
by an order of magnitude at the same ΔK value. We confirmed that almost no oxide was formedin the cracks whereas thick oxide layer was formed in the sample tested in air. From these results,
it should be suggested that the FCG behavior obtained in Ar atmosphere is the nature of thealloys, and the behavior is highly affected by the oxide formation. The underlying mechanism of
FCG will be discussed, in conjunction with the microstructure analyses of the crack tips.
A part of this study was carried under the research of SIP in JST (Japan Science andTechnology Agency).

79

Poster
Influence of grinding depth on the surface integrity and fatigue
properties of γ-TiAl alloys
Renci Liu, Mingjie Ni, Yuyou Cui, Rui Yang
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China

Due to their low ductility and fracture toughness at room temperature, γ-TiAl alloys
are very difficult to machine, and their mechanical properties are very sensitive to thesurface conditions, so it is necessary to study the surface integrity and relate it tofatigue properties of TiAl alloys after surface grinding of cast components. In thisstudy, cast plates of Ti-45Al-2Nb-2Mn-1B alloys were ground with different depth,
their surface integrity, such as surface roughness, microstructure, microhardness, andcorresponding fatigue properties were compared. Cracks were detected in samples
ground with 0.5 mm and 1 mm depth, but not in samples ground with 0.2 mm depth
or below. With increasing grinding depth, the number and depth of groove increased,
and surface roughness parameters Ra and Rz increased, while Rsk decreased. The
γ+α2 lamellae bent in the surface layer, and the bent layer thickness increased withincreasing grinding depth. The microhardness decreased first but increased from thesurface to the interior. The rotating bending fatigue life at 650 oC under a load of 440
MPa decreased with increasing grinding depth: larger than 106 cycles when thegrinding depth was 0.05 mm, but dropped to about 104 cycles when the grinding depth
was 0.2 mm. Fracture surface analysis on the latter showed that the cracks mainly
nucleated at the grooves on the surface, resulting from the stress concentrationinduced by the grooves. The fatigue life decreased with increasing Rz, and it kept
above 106 cycles when Rz was smaller than 4 μm. A nonlinear relationship between
fatigue life and Rz was revealed.

80Poster
Forging process of a large TiAl alloy ingot without envelope
Dong Liu, Renci Liu, Yuyou Cui, Rui Yang
Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China
TiAl alloys have low thermo-plasticity, high deformation resistance, and a very
narrow window of thermal deformation parameters. It is necessary to realize thermal
deformation under near-isothermal conditions under complicated metal envelope
isolation. How to improve the yield of products at an acceptable cost is the focus oftoday's technology developers. This study aims to provide a convenient TiAl alloy
forging method, by using glass lubrication powder high temperature adhesive quick fit
insulation fiber cotton to replace envelope. The design of metal insulation envelope
was thus removed, improving the dimensional accuracy and preparation efficiency ofthe product. Large TiAl alloy ingots with uniform deformation and fine grain size
were obtained by isothermal and low rate deformation.

81

Poster
Embrittlement of -TiAl by oxygen diffusion
Camille Thenot1,2*, Damien Connétable2, Daniel Monceau2, Pierre Sallot3, François Jomard4
and Jean-Philippe Monchoux1*
1

CEMES-CNRS, University of Toulouse, France
2
CIRIMAT, ENSIACET, Toulouse, France
3
SAFRAN TECH, Magny les Hameaux, France
4
GEMAC, Versailles, France*corresponding author

TiAl alloys are sensitive to embrittlement by exposure in air at temperatures around 700°C andfor durations as low as one hour. Though this effect is important for the development of the TiAl
alloys in hot parts of automotive and aeronautical engines, it remains poorly understood. Thus,
we address the questions of the penetration kinetics of oxygen in a Ti-48Al-2Cr-2Nb alloy with anear  microstructure, and its impact on tensile properties at room temperature. For this purpose,tensile specimens have been exposed in a 20 % O2 + 80 %Ar atmosphere, for temperatures
ranging from 400°C to 700°C. The tensile tests show that the embrittlement phenomenon ischaracterized, in addition to the well-known ductility loss effect, by a significant increase in yieldstress. The origin of this increase has been investigated in details looking at microscopic
deformation mechanisms, by transmission electron microscopy. In particular, the dislocation
morphologies have been determined in samples of different oxygen concentrations. The diffusion
coefficient of oxygen in the  phase has been calculated theoretically by DFT to quantify theoxygen penetration kinetics. In parallel, experimental values have been obtained for the first time,using 18O isotope and SIMS concentration profile analyzes. Surprisingly, the experimental
diffusion kinetics were significantly lower than those theoretically predicted. This discrepancy is
discussed in terms of potential effects, based on DFT calculations, of the Nb and Cr substitutional
solutes on the interstitial diffusion mechanisms of oxygen. This study will therefore present key
results enabling to better understand the impact of oxygen dissolution and diffusion in the  phaseon the origin of the increase in yield stress, and its correlation with the embrittlement
phenomenon.

82

Poster
Joining of Ti-42Al-5Mn and S65007 by resistance brazing
Kun Qian1*, Bo Chen1, Lei SHU1, Peng Xue1, Kui LIU1
1

Jihua Laboratory*qiankun@jihualab.ac.cn

In the practical application of TiAl to automobile industries, the joining of TiAl and structuralsteels with excellent wear resistance and toughness are required. Ti-42Al-5Mn and S65007 werejoined by resistance brazing using the active silver-based filler metal of AgCuInTi and AgCuTi
filler alloys, respectively. Brazing was performed in the temperature range of 800 to 900ºC for 30
s by using a Gleeble-3500 thermal simulation testing machine. The tensile strength of the joints
was determined and the microstructure and the chemical composition of the interfaces werestudied by scanning electron microscopy (SEM) and by Electron probe microanalysis (EMPA),
respectively.
Key words: TiAl alloy; S65007; resistance brazing; silver-based filler; tensile strength;83

Poster
Influence of Ni Powder Addition in Sintering Behavior of TiAl Alloy
Powder*Kentaro Shindo1, Akira Fukushima2, Tadayuki Hanada2, Kazuki Hanami3, Kenji Doi3
Hirotoyo Nakashima4, Masao Takeyama4,
Mitsubishi Heavy Industries, Ltd. 2 Mitsubishi Heavy Industries Aero Engines, Ltd. 3Osaka Yakin Kogyo Co. , Ltd. ,4Tokyo Institute of Technology

1*corresponding author

Recently, the development of jet engine parts made of TiAl by Additive Manufacturing (AM)using alloy powder has been promoted, and Metal Injection Molding (MIM) is also attracting
attention because of its freedom of design. In the MIM method, the sinterability of the powder ismost important. Therefore, in this study, the effect of Ni addition on the sinterability of TiAl
alloy powders was investigated by adding Ni powder, which has the effect of lowering themelting point of Ti, and the mechanism of enhancing the sinterability was investigated.
The specimen was compacted TiAl alloy powder of φ28 mm by t5 mm, which was prepared by
EIGA (powder particle size d < 45 µm) and mixed with various amounts of Ni powder in a resinbinder. They were subjected to various sintering heat treatments under Ar atmosphere, anddensity measurements and structural observations were carried out. Some samples were subjected
to DTA to investigate their behavior during sintering and tensile tests to evaluate the integrity ofthe material after sintering.
Fig. 1 shows the effect of Ni addition on the relative density of sintered materials. The relative
density increases sharply with the addition of about 0.5 wt% of Ni, and this tendency appears on
the lower Ni side as the sintering temperature increases. According to the results of the postsintering structural analysis, in the case of a small amount of Ni addition (0.1 wt% Ni), there aremany voids of about 10 µm at the lamellar colony grain boundaries, but when the amount of Ni
addition is 0.6 wt% or more, the voids decrease significantly, resulting in a larger lamellar grain
size (Fig. 2). The less voids, the higher the tensile strength. Therefore, the addition of Ni has asignificant effect on improving the sinterability. From the DTA analysis, the phase diagram of thealloy system and the diffusion coefficients in each phase, the improvement of sinterability by theaddition of Ni is not due to the formation of the liquid phase but to the enhancement of theformation of the beta-Ti phase with a large diffusion coefficient.This study was supported by the
Cross-Ministerial Strategic Innovation Promotion Program (SIP) “Structural Materials forInnovation” from the Japan Science and Technology Agency (JST).

Fig.1 Effect of Ni addition on relative
density of specimens sintered at
1435℃ and 1450°C.

Fig.2 Microstructures sintered at 1450°C: (a) 0.1Ni, (b) 0.6Ni.

84

Poster
Phase Equilibria Between a-Ti/ a2-Ti3Al Phases near 1473 K in TiAl Alloys
Containing Oxygen
Ruona Tang, Hirotoyo Nakashima, Yoshihiro Gohda, Masao Takeyama
Department of Materials Science and Engineering, Tokyo Institute of Technology, Tokyo, Japan

TiAl alloys are characterized by the a2/g lamellar structure formed by the decompositions of thehigh-temperature a (hcp) phase (a→a2 (D019)+g-TiAl (L10)). Microstructure design using thisphase transformation greatly controls the mechanical properties. Especially in the powder process,contamination with oxygen is unavoidable. Thus, understanding of the phase equilibria among
TiAl-based alloys containing oxygen is very important to control the microstructure.
In the previous study, we clarified the effects of oxygen on the phase equilibrium between a/gphases at 1473 K by analyzing the oxygen in each phase by EPMA equipped with a soft X-ray
emission spectroscopy. The phase was uncertain and it is necessary to figure out whether a or a2phase is equilibrated with g phase in this study because even a very low content of oxygen may
affect the stability of a phase and a2 phase. In the Ti-Al binary phase diagram, the phase transition
temperature of a/a2 is 1448 K, which is only 25 K lower than 1473 K. If oxygen is a2 phasestabilizing element, a2 exists at 1473 K. If oxygen is a phase stabilizing element, then a phase
exists at 1473 K.
In this study, we explored the presence of a/a2 phases at 1473 K by using TEM to observe thepresence of APD. Samples with oxygen content at 0.2 and 1.0 at.% were observed and found that
APD with a size of approximately 100 nm is present in the 0.2O sample but not in the 1.0O sample.
That means the 0.2O sample has the ordering process from the a phase to the a2 phase during watercooling from 1473 K, while the 1.0O sample already has the a2 phase in 1473 K. Therefore, oxygen
has the effect of stabilizing the a2 phases.
Phase diagram calculation software named Pandat was used to calculate and the data of the Ti-AlO interaction factor (0LAl:Ti:O, Va) and Al-Al-O interaction factor (0LAl:Al:O, Va) of a2 phase werechanged on the basis of the original database (DB), and a ternary phase diagram that can reproduce
the experimental results to a certain extent was successfully obtained. Although there is still room
for improvement, the a2+a+g three-phase region in our calculation results reflects the experimental
results better than that from the previous DB.

85

Poster
Effect of Microstructure on Oxidation Behavior
of TiAl Alloys at 1023 K
Mitsutoshi Ueda1*, Takuya Ikeda1**, Hirotoyo Nakashima1 and Masao Takeyama1
1

School of Materials and Chemical Technology, Tokyo Institute of Technology*corresponding author**Undergraduate student, Present address: Mazda Motor Corporation

Titanium-aluminide (TiAl) alloys are one of candidate materials for low pressure turbine (LPT)
blades of jet engines. Microstructure of TiAl alloys consists of various phases such as 2,  and and it can be controlled by alloying elements and heat treatments. Optimization of
microstructure is very important to obtain further excellent mechanical properties. There is a
useful design concept for obtaining suitable microstructure. However, there are few attempts toclarify the effect of microstructure on oxidation behavior. This study tries to make clear the
relationship between microstructure and oxidation behavior of TiAl alloys at lower temperatures.
Various TiAl alloys with chromium (Cr) and/or niobium (Nb) and/or oxygen (O) were oxidized
at 1023 K in ambient air for 360 ks (100 h) to evaluate oxidation resistance and to clarify theeffect of microstructure on oxidation behavior. TiAl alloys with both Cr and Nb show goodoxidation resistance in this experimental condition and Nb addition into the alloys is beneficial toobtain better oxidation resistance compared with the addition of Cr. Oxidation resistant is alsoslightly improved by O addition into the alloys. In this study, the effect of microstructure onoxidation behavior of these alloys will be discussed based on various parameters, such as volume
fraction, grain size and lamellar distance, which are obtained from microstructure observation.

86

PosterToughness bottleneck of g-TiAl alloy via integrated computation
H. Wang1,*, C.G. Bai2, D.S. Xu2, Q.-M. Hu2, R. Yang2
1

Interdisciplinary Center for Additive Manufacturing (ICAM), School of Materials and Chemistry,
University of Shanghai for Science and Technology, Shanghai 200093, China
2
Institute of Metal Research, Chinese Academy of Sciences, 110016 Shenyang, China*haowang7@usst.edu.cn

The present work employs integrated computation on various scales to achieve acomprehensive and quantitative understanding of the toughness bottleneck of g-TiAlalloy, aiming at clarifying the atomic-scale origin and providing potential solutions forthe improvement of the overall performance.
1) Intra-grain cracks are not likely to occur through dislocation interactions. The
critical annihilation distance of dipolar dislocations significantly differs fromtraditional estimation and faulted dipoles can be stable over experimental timescales,in full agreement with high-resolution observations.
2) The ductility and fatigue toughness are sensitive to surface defects. The defects
on surfaces and edges cause weakening with various effects depending on defect type,size, position and orientation, while the edge dimples are the most influential. The
effects of surface scratches are orientation and shape sensitive.
3) The fracture toughness is sensitive to the γ/α2 interfaces. The coherency of γ/α2interfaces depend on the thickness ratio of γ lamellae to α2 lamellae, and there exists a
critical lamella thickness, below/above which the interface is coherent/semi-coherent.
Both interfaces exhibit low fracture toughness against perpendicular loading.
Keywords: TiAl; Dislocation dipole; Phase interface; Surface; Mechanical behavior

87Poster
Deep understanding of phase equilibria and CALPHAD modellingin Ti-Al-X (X=Nb, Mo, W, Si, Zr, O, B, C) systems
Yang Yang1*, Anders Engström1, Hai-Lin Chen1, Qing Chen1
1

Thermo-Calc Software AB, Solna, Sweden*Corresponding email: yang@thermocalc.com

Design of new TiAl alloys for turbine blades is crucial in order to meet the goals to reduce CO2
and NOx emissions from turbine jet engines while increasing their efficiency. Many
investigations have been carried out by a variety of experimental techniques in Ti-Al-X systems
and it has been reported that adding Nb, Mo, W, Si, Zr, B, C is beneficial to improve the ductility,
fracture toughness and oxidation resistance in TiAl alloys. In view of alloy development to
optimize the microstructures in these alloys, quantitative data on phase equilibria involving β/βo
(Bcc_A2 or Bcc_B2), γ (TiAl: L10), α2 (Ti3Al: D019) and α (Hcp_A3) would be essential.
Due to the inevitable experimental challenges (unquenchable phase transformations, impurity
contamination, etc.), available data on phase equilibria in the ternary systems Ti-Al-X (X=Nb,
Mo, W, Si, Zr, O, B, C) are often incomplete or contradictory. In order to resolve existing
experimental controversies and to develop a more accurate thermodynamic database, a detailed
understanding of phase equilibria and CALPHAD modelling in these Ti-Al-X systems have beenachieved in the ADVANCE project [1]. The sophisticated experiments performed during the
project resulted in strengthened thermodynamic descriptions for the titanium aluminide systems.
The significantly improved thermodynamic descriptions have been integrated into the TCTI [2]database so that the calculated results can be readily applied to support the design of new,lightweight, high-temperature structural alloys. This presentation will show the majorachievements from the ADVANCE project connected to the development of a state-of-the-art
CALPHAD database for TiAl alloys.
[1] ADVANCE: Sophisticated experiments and optimization to advance an existing CALPHAD
database for next generation TiAl alloys. This project has received funding from the European
Union’s Horizon 2020 research and innovation Program under grant agreement No. 820647.
< https://thermocalc.com/about-us/advance/>[2] Thermo-Calc Software, Titanium and TiAl-based Alloys database, version 5.
< https://thermocalc.com/products/databases/titanium-and-titanium-aluminide-based-alloys/>88IndexPresenting authors & co-authors

89

90

A

D

H

Allen, M., 38, 47, 60

Distl, B., 35

Hanada, T., 42, 44, 65, 84

Andrade, A. de, 25Doi, K., 44, 65, 84

Hanami, K., 44, 65, 84

Antretter, T., 78

Donchev, A., 47, 71

Hantcherli, M., 46

Appel, F., 49, 55
Ask, A., 56

B
Baake, E., 29

Hao, J., 70

E
Elfstrom, I., 58
Engström, A., 63, 88
Epherre, R., 43

Bai, C.G., 87
Bauer, C., 29
Bauer, P.-P., 73
Bewlay, B.P., 21
Beynet, Y, 43
Biamino, S., 62
Bo, C., 64, 70, 83

Hauschildt, K., 35
Helle, O., 72
Hijikata, Y., 52
Holec, D., 32, 38, 66
Hu, Q.M., 87

F
Filippini, M., 53

I

Franz, H., 29

Ikeda, K., 42, 86

Fregeac, A., 43
Fukushima, A., 42, 84

Bouzy, E., 51
Breuner, C., 73

Hatzenbichler, L., 38

Ishida, H., 61
Isomura, R., 79
Iuliano, L., 62

G

Iwasa, Y., 65

Gabrisch, H., 68

C

Galati, M., 62

J

Cao, R., 36, 77

Galetz, M.C., 47, 71

Janosvká, M., 68

Chen, H.-L., 63, 88

Galy. B., 46, 54

Jennings, R., 27

Chen, Q., 63, 88
Cho, K., 57, 59
Clemens, H., 37, 38, 46, 47,
54, 62, 66, 67, 78

Gan, W., 51
Ghibaudo, C., 62

Johansson, S., 58
Jomard, F., 82

Gohda, Y., 33, 34, 85
Gokan, K., 52

Connétable, D., 82

Graf, G., 66, 78

K

Coppola, M., 62

Granhed, E., 58

Kakehi, K., 52

Couret, A., 41, 46, 54

Guth, S., 73

Kanouté, P., 56

Cui, Y., 36, 77, 80, 81

Güther, V., 38, 60

Kardos, S., 38Keïta, M., 51

91

Kim, S.-W., 30

Monceau, D., 82

Klein, T., 37, 67

Monchoux, J.-P., 41, 46, 54,
82

Q

Moritz, J., 24

Qian, K., 83

Kubushiro, K., 28
Kujihashi, A., 65
Kurashige, M., 28

Moulin, J.-F., 51
Musi, M., 38, 46, 47, 54, 66

L
Laska, N., 72

N

R
Rackel, M.W., 25, 26, 68
Ratschbacher, K., 40

Nagata, Y., 27

Read, N., 27

Nakano, T., 57, 59

Rizza, G., 62

Li, X., 64, 70

Nakashima, H., 33, 34, 74,
79, 84, 85, 86

Rosigkeit, J., 25, 78

Liebscher, C.H., 71

Nezaki, K., 27

Limberg, W., 26

Ni, M., 80

S

Lindemann, J., 60

Nishi, N., 65

Sakakibara, Y., 28

Liu, D., 81

Nishikiori, S., 27

Salem, A., 45

Liu, K., 64, 70, 83

Nishimura, T., 61

Sallot, P., 22, 82

Liu, R., 36, 77, 80, 81

Nó, M. L., 37, 67

San Juan, J.M., 37, 67

Lewandowski, J.J., 45
Leyens, C., 24

Lüneburg, H., 26

M

Satko, D., 45

O
Obersteiner, D., 66

Maawad, E., 66

Oehring, M., 55

Mackie, J., 43

Ono, C., 61

Marchese, G., 62

Oskay, C., 71

Marquardt, A., 24

Ota, Y., 27, 28

Schemmel, M., 78
Schulze, S., 26
Sehring, B., 29
Seifi, M., 45
Semiatin, S.L., 45
Shibata, U., 34

Matthiessen, D., 55

Shindo, K., 42, 44, 65, 84

Mengis, L., 71

Shu, L., 83

Mishima, Y., 50

Snis, A., 58

Miyamura, T., 61

P

Sobu, S., 42, 44, 65

Miyoshi, I., 42

Paul, J.D.H., 26, 55

Solís, C., 51

Mizuta, K., 52

Pyczak, F., 25, 26, 35, 49,
55, 68

Sommer, A., 69

Molénat, G., 46, 54

Song, L., 49

92

Spitans, S., 29

Todai, M., 57

Spoerk-Erdely, P., 38, 46,
47, 66, 78

Tooyama, F., 31
Toualbi, L., 46, 54, 56

Stark, A., 25, 38, 66, 68
Staron, P., 25, 66, 78

U

Steinberg, K.H., 26

Ueda, M., 57, 86Swadźba, R., 72, 73

Ugues, D., 62
Ulrich, A.S., 71

Takahashi, S., 28

Xu, D.S., 87
Xue, P., 70, 83

Stein, F., 35

TX

Y
Yamada, Y., 61
Yamagata, R., 33, 74, 79
Yamamoto, H., 42

W

Yamazoe, T., 61
Yang, R., 36, 77, 80, 81, 87

Takeyama, M., 23, 28, 33,
34, 50, 57, 59, 74, 79, 84,
85, 86

Wakabayashi, H., 31

Yang, Y., 63, 88

Walther, F., 24

Yasuda, H.Y., 57, 59

Tang, R., 85

Wang, H., 87

Terauchi, S., 65

Wartbichler, R., 62

Teschke, M., 24

Watermeyer, P., 71

Tetsui, T., 48

Weimer, M.J., 21

Thenot, C., 82
Thomas, M., 39, 41, 46, 54

Z
Zhang, M., 64
Zhang, T., 49
Zhang, Y., 51, 69
Zhou, Z., 36

93

94

IndexParticipants

95

96

AllenBewlayBiaminoBouzy
Breuner
Cho
Clemens
CouretDoi
Donchev
Elfstroem
Engström
Filippini
Fregeac
Fukushima
GabrischGalatiGaletz
Gohda
Graf
Guether
HanadaHanami
Hantcherli
Hemptel
Holec
IshidaJennings
Kakehi
KanedaKanoute
Keita
Kim
Kurashige
Laska
Lewandowski
Leyens
Li
Liu
Liu
Liu
Lu
MizutaMolénatMonchoux
Musi

Melissa Hannah
BernardSara
Emmanuel
Christoph
Ken
HelmutAlain
Kenji
Alexander
Isak
Anders
Mauro
ArnaudAkira
Heike
ManuelaMathiasYoshihiro
GloriaVolkerTadayuki
Kazuki
MurielRobertDavid
Hitoshi
RachelKoji
Shintaro
PascaleMohamedSeong-Woong
Masafumi
NadineJohn
Christoph
Xiaobing
Kui
Renci
Dong
Zhengguan
KazuhiroGuy
J-PhilippeMichaelmelissa.allen@gfe.com
bewlay@ge.com
sara.biamino@polito.it
emmanuel.bouzy@univ-lorraine.fr
christoph.breuner@kit.edu
k_cho@mat.eng.osaka-u.ac.jp
helmut.clemens@unileoben.ac.atalain.couret@cemes.fr
doi@e.osakayakin.co.jp
donchev@dechema.de
isak.elfstrom@ge.com
anders@thermocalc.se
mauro.filippini@polimi.it
fregeac@norimat.com
akira.fukushima.u7@mhi.com
heike.gabrisch@hereon.demanuela.galati@polito.it
galetz@dechema.de
gohda.y.ab@m.titech.ac.jp
gloria.graf@unileoben.ac.at
margit.volker@kabelmail.detadayuki.hanada.v8@mhi.com
hanami@e.osakayakin.co.jp
muriel.hantcherli@cemes.frrobert.hempel@tibar.de
david.holec@unileoben.ac.at
ishida.hitoshi@kobelco.com
jennings8328@ihi-g.com
kkakehi@tmu.ac.jp
shintaro.kaneda@aeroedge.co.jp
Pascale.Kanoute@onera.fr
mohamed.keita@hereon.demrbass@kims.re.kr
kursahige6552@ihi-g.com
Nadine.Laska@dlr.de
jjl3@case.edu
christoph.leyens@iws.fraunhofer.de
lixb@jihualab.ac.cn
liukui@jihualab.ac.cn
rcliu@imr.ac.cn
dliu@imr.ac.cn
zglu@imr.ac.cn
kazuhiro.mizuta@aeroedge.co.jp
guy.molenat@cemes.fr
jean-philippe.monchoux@cemes.fr
michael.musi@unileoben.ac.at97

NagataNakashima
Nishikiori
Nishimura
No
Paul
Pinto Mora
PyczakQian
RackelRatschbacher
SallotSan JuanSchmidShindoShu
SmarslySong
Spitans
Spoerk-Erdely
Stein
TaharaTakeyama
Tang
TerauchiTerauchi
TetsuiThomasTooyama
Ueda
Wakabayashi
Wang
Wu
Xu
Yamagata
Yang
Yang
Yasuda
Young
Zhang
Zhang
Zhang

YoshihikoHirotoyo
Sadao
Tomohiro
Maria
JonathanAliz Maria
FlorianKun
MarcusKarin
PierreJoséPhilipp
KentaroLei
Wilfried
Lin
SergejsPetra
Frank
Kazunori
Masao
Ruona
Shuntaro
Ikuko
Toshimitsu
Marc
Fumio
Mitsutoshi
Hideki
Hao
Jie
Lei
RyosukeRui
Yang
HiroyukiAdam
YuzhengMengshu
Yudongnagata7192@ihi-g.com
nakashima.h.aa@m.titech.ac.jp
nishikiori8375@ihi-g.com
nishimura.tomohiro@kobelco.com
maria.no@ehu.es
jonathan.paul@hereon.de
aliz.pinto-mora@safrangroup.com
Florian.Pyczak@hzg.de
qiankun@jihualab.ac.cn
marcus.rackel@hzg.dekarin.ratschbacher@gfe.com
pierre.sallot@safrangroup.com
jose.sanjuan@ehu.essusanne.kramm@gfe.com
kentaro.shindo.fj@mhi.com
shulei@jihualab.com
wilfried.smarsly@t-online.desonglin@nwpu.edu.cn
sergejs.spitans@ald-vt.depetra.spoerk-erdely@unileoben.ac.at
stein@mpie.detahara9719@ihi-g.com
takeyama@mtl.titech.ac.jp
tang.r.ab@m.titech.ac.jp
terauchi@e.osakayakin.co.jp
doiken1027@hera.eonet.ne.jp
TETSUI.Toshimitsu@nims.go.jp
marc.thomas@onera.fr
tooyama_f@kiguchitech.co.jp
mueda@mtl.titech.ac.jp
hwakabayashi@riko.shimane-u.ac.jp
hao.wang.7@icloud.com
jwu10s@imr.ac.cn
lxu@imr.ac.cn
yamagata.r.aa@m.titech.ac.jp
ryang@imr.ac.cn
yang@thermocalc.com
hyyasuda@mat.eng.osaka-u.ac.jp
adam.young@cbmm.com
yuzheng.zhang@delwestusa.com
liukui@jihualab.ac.cn
yudong.zhang@univ-lorraine.fr98Notes

99

100

101

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